diff --git a/app/assets/javascripts/pages/users/user_tabs.js b/app/assets/javascripts/pages/users/user_tabs.js
index e3aac07097bb1e275eddae3a69244be6df8efb24..80e14842f515bee0f17f5e9d019f4277627b0756 100644
--- a/app/assets/javascripts/pages/users/user_tabs.js
+++ b/app/assets/javascripts/pages/users/user_tabs.js
@@ -141,7 +141,15 @@ export default class UserTabs {
       this.loadOverviewTab();
     }
 
-    const loadableActions = ['groups', 'contributed', 'projects', 'starred', 'snippets'];
+    const loadableActions = [
+      'groups',
+      'contributed',
+      'projects',
+      'starred',
+      'snippets',
+      'followers',
+      'following',
+    ];
     if (loadableActions.indexOf(action) > -1) {
       this.loadTab(action, endpoint);
     }
diff --git a/app/controllers/dashboard_controller.rb b/app/controllers/dashboard_controller.rb
index a88cf64d8426b23b2c9323d05545010330b45e73..29cb60ad3ccdfc32a77a6d23332a160147f77322 100644
--- a/app/controllers/dashboard_controller.rb
+++ b/app/controllers/dashboard_controller.rb
@@ -33,6 +33,21 @@ def activity
   protected
 
   def load_events
+    @events =
+      if params[:filter] == "followed"
+        load_user_events
+      else
+        load_project_events
+      end
+
+    Events::RenderService.new(current_user).execute(@events)
+  end
+
+  def load_user_events
+    UserRecentEventsFinder.new(current_user, current_user.followees, event_filter, params).execute
+  end
+
+  def load_project_events
     projects =
       if params[:filter] == "starred"
         ProjectsFinder.new(current_user: current_user, params: { starred: true }).execute
@@ -40,12 +55,10 @@ def load_events
         current_user.authorized_projects
       end
 
-    @events = EventCollection
+    EventCollection
       .new(projects, offset: params[:offset].to_i, filter: event_filter)
       .to_a
       .map(&:present)
-
-    Events::RenderService.new(current_user).execute(@events)
   end
 
   def set_show_full_reference
diff --git a/app/controllers/users_controller.rb b/app/controllers/users_controller.rb
index c91521286386c348d43b2131a1d4df4012c258d3..54d97f588fca77e0a25c20b64ffb73d763842000 100644
--- a/app/controllers/users_controller.rb
+++ b/app/controllers/users_controller.rb
@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 class UsersController < ApplicationController
+  include InternalRedirect
   include RoutableActions
   include RendersMemberAccess
   include RendersProjectsList
@@ -13,13 +14,15 @@ class UsersController < ApplicationController
                                 contributed: false,
                                 snippets: true,
                                 calendar: false,
+                                followers: false,
+                                following: false,
                                 calendar_activities: true
 
   skip_before_action :authenticate_user!
   prepend_before_action(only: [:show]) { authenticate_sessionless_user!(:rss) }
   before_action :user, except: [:exists, :suggests, :ssh_keys]
   before_action :authorize_read_user_profile!,
-                only: [:calendar, :calendar_activities, :groups, :projects, :contributed, :starred, :snippets]
+                only: [:calendar, :calendar_activities, :groups, :projects, :contributed, :starred, :snippets, :followers, :following]
 
   feature_category :users
 
@@ -97,6 +100,18 @@ def starred
     present_projects(@starred_projects)
   end
 
+  def followers
+    @user_followers = user.followers.page(params[:page])
+
+    present_users(@user_followers)
+  end
+
+  def following
+    @user_following = user.followees.page(params[:page])
+
+    present_users(@user_following)
+  end
+
   def present_projects(projects)
     skip_pagination = Gitlab::Utils.to_boolean(params[:skip_pagination])
     skip_namespace = Gitlab::Utils.to_boolean(params[:skip_namespace])
@@ -146,6 +161,22 @@ def suggests
     render json: { exists: exists, suggests: suggestions }
   end
 
+  def follow
+    current_user.follow(user)
+
+    redirect_path = referer_path(request) || @user
+
+    redirect_to redirect_path
+  end
+
+  def unfollow
+    current_user.unfollow(user)
+
+    redirect_path = referer_path(request) || @user
+
+    redirect_to redirect_path
+  end
+
   private
 
   def user
@@ -169,7 +200,7 @@ def contributions_calendar
   end
 
   def load_events
-    @events = UserRecentEventsFinder.new(current_user, user, params).execute
+    @events = UserRecentEventsFinder.new(current_user, user, nil, params).execute
 
     Events::RenderService.new(current_user).execute(@events, atom_request: request.format.atom?)
   end
@@ -216,6 +247,17 @@ def build_canonical_path(user)
   def authorize_read_user_profile!
     access_denied! unless can?(current_user, :read_user_profile, user)
   end
+
+  def present_users(users)
+    respond_to do |format|
+      format.html { render 'show' }
+      format.json do
+        render json: {
+          html: view_to_html_string("shared/users/index", users: users)
+        }
+      end
+    end
+  end
 end
 
 UsersController.prepend_if_ee('EE::UsersController')
diff --git a/app/finders/user_recent_events_finder.rb b/app/finders/user_recent_events_finder.rb
index c9a1c918365766d830bfca853e47f9ddda2b2cb6..596a413782e5ba17b3f17d13e30e5228f12bbb3c 100644
--- a/app/finders/user_recent_events_finder.rb
+++ b/app/finders/user_recent_events_finder.rb
@@ -15,27 +15,49 @@ class UserRecentEventsFinder
 
   requires_cross_project_access
 
-  attr_reader :current_user, :target_user, :params
+  attr_reader :current_user, :target_user, :params, :event_filter
 
   DEFAULT_LIMIT = 20
   MAX_LIMIT = 100
 
-  def initialize(current_user, target_user, params = {})
+  def initialize(current_user, target_user, event_filter, params = {})
     @current_user = current_user
     @target_user = target_user
     @params = params
+    @event_filter = event_filter || EventFilter.new(EventFilter::ALL)
   end
 
   def execute
+    if target_user.is_a? User
+      execute_single
+    else
+      execute_multi
+    end
+  end
+
+  private
+
+  def execute_single
     return Event.none unless can?(current_user, :read_user_profile, target_user)
 
-    target_events
+    event_filter.apply_filter(target_events
       .with_associations
       .limit_recent(limit, params[:offset])
-      .order_created_desc
+      .order_created_desc)
   end
 
-  private
+  # rubocop: disable CodeReuse/ActiveRecord
+  def execute_multi
+    users = []
+    @target_user.each do |user|
+      users.append(user.id) if can?(current_user, :read_user_profile, user)
+    end
+
+    return Event.none if users.empty?
+
+    event_filter.apply_filter(Event.where(author: users).limit_recent(limit, params[:offset] || 0))
+  end
+  # rubocop: enable CodeReuse/ActiveRecord
 
   # rubocop: disable CodeReuse/ActiveRecord
   def target_events
diff --git a/app/helpers/users_helper.rb b/app/helpers/users_helper.rb
index 1ea2d4412b1603ccb7bf0550599205bf0e055111..1979426f844ba0d43ab26a3be7930627d679c7dc 100644
--- a/app/helpers/users_helper.rb
+++ b/app/helpers/users_helper.rb
@@ -242,7 +242,7 @@ def get_profile_tabs
     tabs = []
 
     if can?(current_user, :read_user_profile, @user)
-      tabs += [:overview, :activity, :groups, :contributed, :projects, :starred, :snippets]
+      tabs += [:overview, :activity, :groups, :contributed, :projects, :starred, :snippets, :followers, :following]
     end
 
     tabs
diff --git a/app/models/user.rb b/app/models/user.rb
index 4a2ca64fbe97ef78e8addf4ba34fb4eb291576e2..1f8b680c7e5e475a75a1e2dacfda0602a76f62a1 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -116,6 +116,13 @@ def update_tracked_fields!(request)
   has_one :user_synced_attributes_metadata, autosave: true
   has_one :aws_role, class_name: 'Aws::Role'
 
+  # Followers
+  has_many :followed_users, foreign_key: :follower_id, class_name: 'Users::UserFollowUser'
+  has_many :followees, through: :followed_users
+
+  has_many :following_users, foreign_key: :followee_id, class_name: 'Users::UserFollowUser'
+  has_many :followers, through: :following_users
+
   # Groups
   has_many :members
   has_many :group_members, -> { where(requested_at: nil).where("access_level >= ?", Gitlab::Access::GUEST) }, source: 'GroupMember'
@@ -1442,6 +1449,29 @@ def toggle_star(project)
     end
   end
 
+  def following?(user)
+    self.followees.exists?(user.id)
+  end
+
+  def follow(user)
+    return false if self.id == user.id
+
+    begin
+      followee = Users::UserFollowUser.create(follower_id: self.id, followee_id: user.id)
+      self.followees.reset if followee.persisted?
+    rescue ActiveRecord::RecordNotUnique
+      false
+    end
+  end
+
+  def unfollow(user)
+    if Users::UserFollowUser.where(follower_id: self.id, followee_id: user.id).delete_all > 0
+      self.followees.reset
+    else
+      false
+    end
+  end
+
   def manageable_namespaces
     @manageable_namespaces ||= [namespace] + manageable_groups
   end
diff --git a/app/models/users/user_follow_user.rb b/app/models/users/user_follow_user.rb
new file mode 100644
index 0000000000000000000000000000000000000000..a94239a746c380e920db4ad1d5c7ec2ffcb9e62f
--- /dev/null
+++ b/app/models/users/user_follow_user.rb
@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+module Users
+  class UserFollowUser < ApplicationRecord
+    belongs_to :follower, class_name: 'User'
+    belongs_to :followee, class_name: 'User'
+  end
+end
diff --git a/app/views/dashboard/_activity_head.html.haml b/app/views/dashboard/_activity_head.html.haml
index 3f39555a1d4af84aee99a7c54c99b100690ce1b0..0daadd20f54c20ad7406c1c96876078229a18cf3 100644
--- a/app/views/dashboard/_activity_head.html.haml
+++ b/app/views/dashboard/_activity_head.html.haml
@@ -5,7 +5,10 @@
   %ul.nav-links.nav.nav-tabs
     %li{ class: active_when(params[:filter].nil?) }>
       = link_to activity_dashboard_path, class: 'shortcuts-activity', data: {placement: 'right'} do
-        Your projects
+        = _('Your projects')
     %li{ class: active_when(params[:filter] == 'starred') }>
       = link_to activity_dashboard_path(filter: 'starred'), data: {placement: 'right'} do
-        Starred projects
+        = _('Starred projects')
+    %li{ class: active_when(params[:filter] == 'followed') }>
+      = link_to activity_dashboard_path(filter: 'followed'), data: {placement: 'right'} do
+        = _('Followed users')
diff --git a/app/views/shared/empty_states/_profile_tabs.html.haml b/app/views/shared/empty_states/_profile_tabs.html.haml
index 7780a144a26d83f3f4c98ca95d206d3c34fcbba4..abcf9740200a38d6c34f2254177295e51a91ba61 100644
--- a/app/views/shared/empty_states/_profile_tabs.html.haml
+++ b/app/views/shared/empty_states/_profile_tabs.html.haml
@@ -1,5 +1,6 @@
 - current_user_empty_message_description = local_assigns.fetch(:current_user_empty_message_description, nil)
 - secondary_button_link = local_assigns.fetch(:secondary_button_link, nil)
+- primary_button_link = local_assigns.fetch(:primary_button_link, nil)
 
 .nothing-here-block
   .svg-content
diff --git a/app/views/shared/users/_user.html.haml b/app/views/shared/users/_user.html.haml
new file mode 100644
index 0000000000000000000000000000000000000000..f92c12102bb338520b6d444dde97750668555603
--- /dev/null
+++ b/app/views/shared/users/_user.html.haml
@@ -0,0 +1,13 @@
+- user = local_assigns.fetch(:user)
+
+.col-lg-3.col-md-4.col-sm-12
+  .gl-card.gl-mb-5
+    .gl-card-body
+      = image_tag avatar_icon_for_user(user, 40), class: "avatar s40", alt: ''
+
+      .user-info
+        .block-truncated
+          = link_to user.name, user_path(user), class: 'user js-user-link', data: { user_id: user.id }
+
+        .block-truncated
+          %span.gl-text-gray-900= user.to_reference
diff --git a/app/views/shared/users/index.html.haml b/app/views/shared/users/index.html.haml
new file mode 100644
index 0000000000000000000000000000000000000000..dd6b14d6be2f1ae1c494665dbe017f14454d4208
--- /dev/null
+++ b/app/views/shared/users/index.html.haml
@@ -0,0 +1,20 @@
+- followers_illustration_path = 'illustrations/starred_empty.svg'
+- followers_visitor_empty_message = s_('UserProfile|This user doesn\'t have any followers.')
+- followers_current_user_empty_message_header = s_('UserProfile|You do not have any followers.')
+- following_illustration_path = 'illustrations/starred_empty.svg'
+- following_visitor_empty_message = s_('UserProfile|This user isn\'t following other users.')
+- following_current_user_empty_message_header = s_('UserProfile|You are not following other users.')
+
+- if users.size > 0
+  .row.gl-mt-3
+    = render partial: 'shared/users/user', collection: users, as: :user
+  = paginate users, theme: 'gitlab'
+- else
+  - if @user_followers
+    = render partial: 'shared/empty_states/profile_tabs', locals: { illustration_path: followers_illustration_path,
+      visitor_empty_message: followers_visitor_empty_message,
+      current_user_empty_message_header: followers_current_user_empty_message_header}
+  - elsif @user_following
+    = render partial: 'shared/empty_states/profile_tabs', locals: { illustration_path: following_illustration_path,
+      visitor_empty_message: following_visitor_empty_message,
+      current_user_empty_message_header: following_current_user_empty_message_header}
diff --git a/app/views/users/show.html.haml b/app/views/users/show.html.haml
index debfe57dbd78fbc5560cce1ffb0b4736175c3a7f..cdaa739a7b36d06e74634aba56edd4ad3af456e5 100644
--- a/app/views/users/show.html.haml
+++ b/app/views/users/show.html.haml
@@ -26,6 +26,13 @@
           = link_to new_abuse_report_path(user_id: @user.id, ref_url: request.referrer), class: link_classes + 'btn gl-button btn-default btn-icon',
             title: s_('UserProfile|Report abuse'), data: { toggle: 'tooltip', placement: 'bottom', container: 'body' } do
             = sprite_icon('error')
+      - if current_user && current_user.id != @user.id
+        - if current_user.following?(@user)
+          = link_to user_unfollow_path(@user, :json) , class: link_classes + 'btn gl-button btn-default', method: :post do
+            = _('Unfollow')
+        - else
+          = link_to user_follow_path(@user, :json) , class: link_classes + 'btn gl-button btn-default', method: :post do
+            = _('Follow')
       - if can?(current_user, :read_user_profile, @user)
         = link_to user_path(@user, rss_url_options), class: link_classes + 'btn gl-button btn-default btn-icon has-tooltip',
           title: s_('UserProfile|Subscribe'), data: { toggle: 'tooltip', placement: 'bottom', container: 'body' } do
@@ -89,6 +96,16 @@
             - unless @user.public_email.blank?
               .profile-link-holder.middle-dot-divider-sm.d-block.d-sm-inline.mt-1.mt-sm-0
                 = link_to @user.public_email, "mailto:#{@user.public_email}", class: 'text-link', itemprop: 'email'
+          .cover-desc.gl-text-gray-900.gl-mb-2.mb-sm-2
+            = sprite_icon('users', css_class: 'gl-vertical-align-middle gl-text-gray-500')
+            .profile-link-holder.middle-dot-divider
+              = link_to user_followers_path, class: 'text-link' do
+                - count = @user.followers.count
+                = n_('1 follower', '%{count} followers', count) % { count: count }
+            .profile-link-holder.middle-dot-divider
+              = link_to user_following_path, class: 'text-link' do
+                = @user.followees.count
+                = _('following')
         - if @user.bio.present?
           .cover-desc.cgray
             .profile-user-bio
@@ -129,6 +146,14 @@
               %li.js-snippets-tab
                 = link_to user_snippets_path, data: { target: 'div#snippets', action: 'snippets', toggle: 'tab', endpoint: user_snippets_path(format: :json) } do
                   = s_('UserProfile|Snippets')
+            - if profile_tab?(:followers)
+              %li.js-followers-tab
+                = link_to user_followers_path, data: { target: 'div#followers', action: 'followers', toggle: 'tab', endpoint: user_followers_path(format: :json) } do
+                  = s_('UserProfile|Followers')
+            - if profile_tab?(:following)
+              %li.js-following-tab
+                = link_to user_following_path, data: { target: 'div#following', action: 'following', toggle: 'tab', endpoint: user_following_path(format: :json) } do
+                  = s_('UserProfile|Following')
 
   %div{ class: container_class }
     .tab-content
@@ -165,6 +190,14 @@
           #snippets.tab-pane
             -# This tab is always loaded via AJAX
 
+        - if profile_tab?(:followers)
+          #followers.tab-pane
+            -# This tab is always loaded via AJAX
+
+        - if profile_tab?(:following)
+          #following.tab-pane
+            -# This tab is always loaded via AJAX
+
     .loading.hide
       .spinner.spinner-md
 
diff --git a/changelogs/unreleased/feat-follow-eachother.yml b/changelogs/unreleased/feat-follow-eachother.yml
new file mode 100644
index 0000000000000000000000000000000000000000..ba80e35535ead8961319e9e0eb079bb2065b345c
--- /dev/null
+++ b/changelogs/unreleased/feat-follow-eachother.yml
@@ -0,0 +1,5 @@
+---
+title: Add follow each other model, API and UI(profile, activity view)
+merge_request: 45451
+author: Roger Meier
+type: added
diff --git a/config/routes/user.rb b/config/routes/user.rb
index 515a9a23360c5ea28478f75476dea36a80d3a628..41319b6d730d13ae38bcbd0fff1449c9cd02e93e 100644
--- a/config/routes/user.rb
+++ b/config/routes/user.rb
@@ -46,9 +46,13 @@ def override_omniauth(provider, controller, path_prefix = '/users/auth')
     get :contributed, as: :contributed_projects
     get :starred, as: :starred_projects
     get :snippets
+    get :followers
+    get :following
     get :exists
     get :suggests
     get :activity
+    post :follow
+    post :unfollow
     get '/', to: redirect('%{username}'), as: nil
   end
 end
diff --git a/db/migrate/20201027101010_create_user_follow_users.rb b/db/migrate/20201027101010_create_user_follow_users.rb
new file mode 100644
index 0000000000000000000000000000000000000000..7c1f831f3b25e2d8523083c05537bcc8f97faccf
--- /dev/null
+++ b/db/migrate/20201027101010_create_user_follow_users.rb
@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+class CreateUserFollowUsers < ActiveRecord::Migration[6.0]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  def up
+    with_lock_retries do
+      execute <<~SQL
+        CREATE TABLE user_follow_users (
+          follower_id integer not null references users (id) on delete cascade,
+          followee_id integer not null references users (id) on delete cascade,
+          PRIMARY KEY (follower_id, followee_id)
+        );
+        CREATE INDEX ON user_follow_users (followee_id);
+      SQL
+    end
+  end
+
+  def down
+    drop_table :user_follow_users
+  end
+end
diff --git a/db/schema_migrations/20201027101010 b/db/schema_migrations/20201027101010
new file mode 100644
index 0000000000000000000000000000000000000000..68628373757f85a3be6f5b4082c889c907f27379
--- /dev/null
+++ b/db/schema_migrations/20201027101010
@@ -0,0 +1 @@
+d6b324e808265c4ba8b6216c77b7abfa96b4b8b4c9fbd8d0a15240548526c4f3
\ No newline at end of file
diff --git a/db/structure.sql b/db/structure.sql
index 91efc451e202c0f709cc27e3891f7e05bbda131f..5d27baaab020c99cdcf340b99466ce2cc1372ba2 100644
--- a/db/structure.sql
+++ b/db/structure.sql
@@ -17751,6 +17751,11 @@ CREATE SEQUENCE user_details_user_id_seq
 
 ALTER SEQUENCE user_details_user_id_seq OWNED BY user_details.user_id;
 
+CREATE TABLE user_follow_users (
+    follower_id integer NOT NULL,
+    followee_id integer NOT NULL
+);
+
 CREATE TABLE user_highest_roles (
     user_id bigint NOT NULL,
     updated_at timestamp with time zone NOT NULL,
@@ -20917,6 +20922,9 @@ ALTER TABLE ONLY user_custom_attributes
 ALTER TABLE ONLY user_details
     ADD CONSTRAINT user_details_pkey PRIMARY KEY (user_id);
 
+ALTER TABLE ONLY user_follow_users
+    ADD CONSTRAINT user_follow_users_pkey PRIMARY KEY (follower_id, followee_id);
+
 ALTER TABLE ONLY user_highest_roles
     ADD CONSTRAINT user_highest_roles_pkey PRIMARY KEY (user_id);
 
@@ -23774,6 +23782,8 @@ CREATE UNIQUE INDEX uniq_pkgs_debian_project_distributions_project_id_and_suite
 
 CREATE UNIQUE INDEX unique_merge_request_metrics_by_merge_request_id ON merge_request_metrics USING btree (merge_request_id);
 
+CREATE INDEX user_follow_users_followee_id_idx ON user_follow_users USING btree (followee_id);
+
 CREATE UNIQUE INDEX vulnerability_feedback_unique_idx ON vulnerability_feedback USING btree (project_id, category, feedback_type, project_fingerprint);
 
 CREATE UNIQUE INDEX vulnerability_occurrence_pipelines_on_unique_keys ON vulnerability_occurrence_pipelines USING btree (occurrence_id, pipeline_id);
@@ -26194,6 +26204,12 @@ ALTER TABLE ONLY u2f_registrations
     ADD CONSTRAINT fk_u2f_registrations_user_id FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE;
 
 ALTER TABLE product_analytics_events_experimental
-    ADD CONSTRAINT product_analytics_events_experimental_project_id_fkey FOREIGN KEY (project_id) REFERENCES projects(id) ON DELETE CASCADE;-- schema_migrations.version information is no longer stored in this file,
+    ADD CONSTRAINT product_analytics_events_experimental_project_id_fkey FOREIGN KEY (project_id) REFERENCES projects(id) ON DELETE CASCADE;
+
+ALTER TABLE ONLY user_follow_users
+    ADD CONSTRAINT user_follow_users_followee_id_fkey FOREIGN KEY (followee_id) REFERENCES users(id) ON DELETE CASCADE;
+
+ALTER TABLE ONLY user_follow_users
+    ADD CONSTRAINT user_follow_users_follower_id_fkey FOREIGN KEY (follower_id) REFERENCES users(id) ON DELETE CASCADE;-- schema_migrations.version information is no longer stored in this file,
 -- but instead tracked in the db/schema_migrations directory
 -- see https://gitlab.com/gitlab-org/gitlab/-/issues/218590 for details
diff --git a/doc/api/users.md b/doc/api/users.md
index d09070081293029a520499957069df596209ef41..60db3be5e8876df107ae9a57969e1c41432daa0c 100644
--- a/doc/api/users.md
+++ b/doc/api/users.md
@@ -274,7 +274,9 @@ Parameters:
   "twitter": "",
   "website_url": "",
   "organization": "",
-  "job_title": "Operations Specialist"
+  "job_title": "Operations Specialist",
+  "followers": 1,
+  "following": 1
 }
 ```
 
@@ -685,6 +687,88 @@ Example responses
 }
 ```
 
+## User Follow
+
+### Follow and unfollow users
+
+Follow a user.
+
+```plaintext
+POST /users/:id/follow
+```
+
+Unfollow a user.
+
+```plaintext
+POST /users/:id/unfollow
+```
+
+| Attribute | Type    | Required | Description                  |
+| --------- | ------- | -------- | ---------------------------- |
+| `id`      | integer | yes      | The ID of the user to follow |
+
+```shell
+curl --request POST --header "PRIVATE-TOKEN: <your_access_token>" "https://gitlab.example.com/users/3/follow"
+```
+
+Example response:
+
+```json
+{
+  "id": 1,
+  "username": "john_smith",
+  "name": "John Smith",
+  "state": "active",
+  "avatar_url": "http://localhost:3000/uploads/user/avatar/1/cd8.jpeg",
+  "web_url": "http://localhost:3000/john_smith"
+}
+```
+
+### Followers and following
+
+Get the followers of a user.
+
+```plaintext
+GET /users/:id/followers
+```
+
+Get the list of users being followed.
+
+```plaintext
+GET /users/:id/following
+```
+
+| Attribute | Type    | Required | Description                  |
+| --------- | ------- | -------- | ---------------------------- |
+| `id`      | integer | yes      | The ID of the user to follow |
+
+```shell
+curl --request GET --header "PRIVATE-TOKEN: <your_access_token>"  "https://gitlab.example.com/users/3/followers"
+```
+
+Example response:
+
+```json
+[
+  {
+    "id": 2,
+    "name": "Lennie Donnelly",
+    "username": "evette.kilback",
+    "state": "active",
+    "avatar_url": "https://www.gravatar.com/avatar/7955171a55ac4997ed81e5976287890a?s=80&d=identicon",
+    "web_url": "http://127.0.0.1:3000/evette.kilback"
+  },
+  {
+    "id": 4,
+    "name": "Serena Bradtke",
+    "username": "cammy",
+    "state": "active",
+    "avatar_url": "https://www.gravatar.com/avatar/a2daad869a7b60d3090b7b9bef4baf57?s=80&d=identicon",
+    "web_url": "http://127.0.0.1:3000/cammy"
+  }
+]
+```
+
 ## User counts
 
 Get the counts (same as in top right menu) of the currently signed in user.
diff --git a/doc/user/img/activity_followed_users_v13_9.png b/doc/user/img/activity_followed_users_v13_9.png
new file mode 100644
index 0000000000000000000000000000000000000000..7f54f17821c3164bb8486d60e10c8e80e0e69bce
Binary files /dev/null and b/doc/user/img/activity_followed_users_v13_9.png differ
diff --git a/doc/user/index.md b/doc/user/index.md
index 598c47963b52acf6b9d0aa440b79c5da85b45eb0..a678038507f8930b4fde0010c00338ca010a542b 100644
--- a/doc/user/index.md
+++ b/doc/user/index.md
@@ -83,6 +83,14 @@ There are several types of users in GitLab:
   self-managed instances' features and settings.
 - [Internal users](../development/internal_users.md).
 
+## User activity
+
+You can follow or unfollow other users from their [user profiles](profile/index.md#user-profile).
+To see their activity in the top-level Activity view, select Follow or Unfollow, and select
+the Followed Users tab:
+
+![Follow users](img/activity_followed_users_v13_9.png)
+
 ## Projects
 
 In GitLab, you can create [projects](project/index.md) to host
diff --git a/doc/user/profile/img/profile_following_v13_9.png b/doc/user/profile/img/profile_following_v13_9.png
new file mode 100644
index 0000000000000000000000000000000000000000..85d54ff3aad7934e8307a49c7fd9c1f2bc93b49f
Binary files /dev/null and b/doc/user/profile/img/profile_following_v13_9.png differ
diff --git a/doc/user/profile/index.md b/doc/user/profile/index.md
index 1ca6f968e9055ddee1fffc3047f26c1471c5b0ab..d2cbf9e4acdbf224cdab438a38c9f8e7b88efe86 100644
--- a/doc/user/profile/index.md
+++ b/doc/user/profile/index.md
@@ -41,6 +41,12 @@ On your profile page, you can see the following information:
 - Personal projects: your personal projects (respecting the project's visibility level)
 - Starred projects: projects you starred
 - Snippets: your personal code [snippets](../snippets.md#personal-snippets)
+- Followers: people following you
+- Following: people you are following
+
+Profile page with active Following view:
+
+![Follow users](img/profile_following_v13_9.png)
 
 ## User settings
 
diff --git a/ee/spec/finders/ee/user_recent_events_finder_spec.rb b/ee/spec/finders/ee/user_recent_events_finder_spec.rb
index 4fcd9d233fe49a5f211ec45cb0c29aeefe6704ac..d46f6d4f5227ce92e9cb3878c5959fa7e858af61 100644
--- a/ee/spec/finders/ee/user_recent_events_finder_spec.rb
+++ b/ee/spec/finders/ee/user_recent_events_finder_spec.rb
@@ -12,7 +12,7 @@
     let_it_be(:public_event) { create(:event, :commented, target: note, author: user, project: nil) }
     let_it_be(:private_event) { create(:event, :closed, target: private_epic, author: user, project: nil) }
 
-    subject { described_class.new(current_user, user, {}).execute }
+    subject { described_class.new(current_user, user, nil, {}).execute }
 
     context 'epic related activities' do
       context 'when profile is public' do
diff --git a/lib/api/entities/user.rb b/lib/api/entities/user.rb
index b392e7831e5633d28d615bd1cd64a781bdf9c418..248a86751d224f252ab1edad6621b24a570839f1 100644
--- a/lib/api/entities/user.rb
+++ b/lib/api/entities/user.rb
@@ -10,6 +10,12 @@ class User < UserBasic
       expose :work_information do |user|
         work_information(user)
       end
+      expose :followers, if: ->(user, opts) { Ability.allowed?(opts[:current_user], :read_user_profile, user) } do |user|
+        user.followers.count
+      end
+      expose :following, if: ->(user, opts) { Ability.allowed?(opts[:current_user], :read_user_profile, user) } do |user|
+        user.followees.count
+      end
     end
   end
 end
diff --git a/lib/api/users.rb b/lib/api/users.rb
index 0352ddfb214356515f3796cece3ebb44f1658a13..28274d5afb3f85a828a186b452e2c1f6cb18691c 100644
--- a/lib/api/users.rb
+++ b/lib/api/users.rb
@@ -159,6 +159,68 @@ def reorder_users(users)
         present user.status || {}, with: Entities::UserStatus
       end
 
+      desc 'Follow a user' do
+        success Entities::User
+      end
+      params do
+        requires :id, type: Integer, desc: 'The ID of the user'
+      end
+      post ':id/follow', feature_category: :users do
+        user = find_user(params[:id])
+        not_found!('User') unless user
+
+        if current_user.follow(user)
+          present user, with: Entities::UserBasic
+        else
+          not_modified!
+        end
+      end
+
+      desc 'Unfollow a user' do
+        success Entities::User
+      end
+      params do
+        requires :id, type: Integer, desc: 'The ID of the user'
+      end
+      post ':id/unfollow', feature_category: :users do
+        user = find_user(params[:id])
+        not_found!('User') unless user
+
+        if current_user.unfollow(user)
+          present user, with: Entities::UserBasic
+        else
+          not_modified!
+        end
+      end
+
+      desc 'Get the users who follow a user' do
+        success Entities::UserBasic
+      end
+      params do
+        requires :id, type: Integer, desc: 'The ID of the user'
+        use :pagination
+      end
+      get ':id/following', feature_category: :users do
+        user = find_user(params[:id])
+        not_found!('User') unless user && can?(current_user, :read_user_profile, user)
+
+        present paginate(user.followees), with: Entities::UserBasic
+      end
+
+      desc 'Get the followers of a user' do
+        success Entities::UserBasic
+      end
+      params do
+        requires :id, type: Integer, desc: 'The ID of the user'
+        use :pagination
+      end
+      get ':id/followers', feature_category: :users do
+        user = find_user(params[:id])
+        not_found!('User') unless user && can?(current_user, :read_user_profile, user)
+
+        present paginate(user.followers), with: Entities::UserBasic
+      end
+
       desc 'Create a user. Available only for admins.' do
         success Entities::UserWithAdmin
       end
diff --git a/locale/gitlab.pot b/locale/gitlab.pot
index 329ec718cf0e333d77e8e6f26c21873e0a7cd2ee..34825e7ed28d64e1dc872777024e949b9ba0d367 100644
--- a/locale/gitlab.pot
+++ b/locale/gitlab.pot
@@ -1123,6 +1123,11 @@ msgid_plural "%d deploy keys"
 msgstr[0] ""
 msgstr[1] ""
 
+msgid "1 follower"
+msgid_plural "%{count} followers"
+msgstr[0] ""
+msgstr[1] ""
+
 msgid "1 group"
 msgid_plural "%d groups"
 msgstr[0] ""
@@ -12971,6 +12976,12 @@ msgstr ""
 msgid "Folder/%{name}"
 msgstr ""
 
+msgid "Follow"
+msgstr ""
+
+msgid "Followed users"
+msgstr ""
+
 msgid "Font Color"
 msgstr ""
 
@@ -31381,6 +31392,9 @@ msgstr ""
 msgid "Unexpected error"
 msgstr ""
 
+msgid "Unfollow"
+msgstr ""
+
 msgid "Unfortunately, your email message to GitLab could not be processed."
 msgstr ""
 
@@ -32038,6 +32052,12 @@ msgstr ""
 msgid "UserProfile|Explore public groups to find projects to contribute to."
 msgstr ""
 
+msgid "UserProfile|Followers"
+msgstr ""
+
+msgid "UserProfile|Following"
+msgstr ""
+
 msgid "UserProfile|Groups"
 msgstr ""
 
@@ -32080,6 +32100,9 @@ msgstr ""
 msgid "UserProfile|Subscribe"
 msgstr ""
 
+msgid "UserProfile|This user doesn't have any followers."
+msgstr ""
+
 msgid "UserProfile|This user doesn't have any personal projects"
 msgstr ""
 
@@ -32095,6 +32118,9 @@ msgstr ""
 msgid "UserProfile|This user is blocked"
 msgstr ""
 
+msgid "UserProfile|This user isn't following other users."
+msgstr ""
+
 msgid "UserProfile|Unconfirmed user"
 msgstr ""
 
@@ -32104,9 +32130,15 @@ msgstr ""
 msgid "UserProfile|View user in admin area"
 msgstr ""
 
+msgid "UserProfile|You are not following other users."
+msgstr ""
+
 msgid "UserProfile|You can create a group for several dependent projects."
 msgstr ""
 
+msgid "UserProfile|You do not have any followers."
+msgstr ""
+
 msgid "UserProfile|You haven't created any personal projects."
 msgstr ""
 
@@ -34672,6 +34704,9 @@ msgstr[1] ""
 msgid "finding is not found or is already attached to a vulnerability"
 msgstr ""
 
+msgid "following"
+msgstr ""
+
 msgid "for %{link_to_merge_request} with %{link_to_merge_request_source_branch}"
 msgstr ""
 
diff --git a/spec/features/dashboard/activity_spec.rb b/spec/features/dashboard/activity_spec.rb
index b419a063858c813f39f312d24562f43512c4b6a9..e75e661b513726d6a37448112c665b9b7031b566 100644
--- a/spec/features/dashboard/activity_spec.rb
+++ b/spec/features/dashboard/activity_spec.rb
@@ -9,6 +9,26 @@
     sign_in(user)
   end
 
+  context 'tabs' do
+    it 'shows Your Projects' do
+      visit activity_dashboard_path
+
+      expect(find('.top-area .nav-tabs li.active')).to have_content('Your projects')
+    end
+
+    it 'shows Starred Projects' do
+      visit activity_dashboard_path(filter: 'starred')
+
+      expect(find('.top-area .nav-tabs li.active')).to have_content('Starred projects')
+    end
+
+    it 'shows Followed Projects' do
+      visit activity_dashboard_path(filter: 'followed')
+
+      expect(find('.top-area .nav-tabs li.active')).to have_content('Followed users')
+    end
+  end
+
   context 'rss' do
     before do
       visit activity_dashboard_path
diff --git a/spec/features/users/overview_spec.rb b/spec/features/users/overview_spec.rb
index 67216b045045db5d10ca9f1dfa2b301127095e59..902079b7b9345033044eaa7e3c27701162193c11 100644
--- a/spec/features/users/overview_spec.rb
+++ b/spec/features/users/overview_spec.rb
@@ -151,6 +151,132 @@ def push_code_contribution
     end
   end
 
+  describe 'followers section' do
+    describe 'user has no followers' do
+      before do
+        visit user.username
+        page.find('.js-followers-tab a').click
+        wait_for_requests
+      end
+
+      it 'shows an empty followers list with an info message' do
+        page.within('#followers') do
+          expect(page).to have_content('You do not have any followers')
+          expect(page).not_to have_selector('.gl-card.gl-mb-5')
+          expect(page).not_to have_selector('.gl-pagination')
+        end
+      end
+    end
+
+    describe 'user has less then 20 followers' do
+      let(:follower) { create(:user) }
+
+      before do
+        follower.follow(user)
+        visit user.username
+        page.find('.js-followers-tab a').click
+        wait_for_requests
+      end
+
+      it 'shows followers' do
+        page.within('#followers') do
+          expect(page).to have_content(follower.name)
+          expect(page).to have_selector('.gl-card.gl-mb-5')
+          expect(page).not_to have_selector('.gl-pagination')
+        end
+      end
+    end
+
+    describe 'user has more then 20 followers' do
+      let(:other_users) { create_list(:user, 21) }
+
+      before do
+        other_users.each do |follower|
+          follower.follow(user)
+        end
+
+        visit user.username
+        page.find('.js-followers-tab a').click
+        wait_for_requests
+      end
+      it 'shows paginated followers' do
+        page.within('#followers') do
+          other_users.each_with_index do |follower, i|
+            break if i == 20
+
+            expect(page).to have_content(follower.name)
+          end
+          expect(page).to have_selector('.gl-card.gl-mb-5')
+          expect(page).to have_selector('.gl-pagination')
+          expect(page).to have_selector('.gl-pagination .js-pagination-page', count: 2)
+        end
+      end
+    end
+  end
+
+  describe 'following section' do
+    describe 'user is not following others' do
+      before do
+        visit user.username
+        page.find('.js-following-tab a').click
+        wait_for_requests
+      end
+
+      it 'shows an empty following list with an info message' do
+        page.within('#following') do
+          expect(page).to have_content('You are not following other users')
+          expect(page).not_to have_selector('.gl-card.gl-mb-5')
+          expect(page).not_to have_selector('.gl-pagination')
+        end
+      end
+    end
+
+    describe 'user is following less then 20 people' do
+      let(:followee) { create(:user) }
+
+      before do
+        user.follow(followee)
+        visit user.username
+        page.find('.js-following-tab a').click
+        wait_for_requests
+      end
+
+      it 'shows following user' do
+        page.within('#following') do
+          expect(page).to have_content(followee.name)
+          expect(page).to have_selector('.gl-card.gl-mb-5')
+          expect(page).not_to have_selector('.gl-pagination')
+        end
+      end
+    end
+
+    describe 'user is following more then 20 people' do
+      let(:other_users) { create_list(:user, 21) }
+
+      before do
+        other_users.each do |followee|
+          user.follow(followee)
+        end
+
+        visit user.username
+        page.find('.js-following-tab a').click
+        wait_for_requests
+      end
+      it 'shows paginated following' do
+        page.within('#following') do
+          other_users.each_with_index do |followee, i|
+            break if i == 20
+
+            expect(page).to have_content(followee.name)
+          end
+          expect(page).to have_selector('.gl-card.gl-mb-5')
+          expect(page).to have_selector('.gl-pagination')
+          expect(page).to have_selector('.gl-pagination .js-pagination-page', count: 2)
+        end
+      end
+    end
+  end
+
   describe 'bot user' do
     let(:bot_user) { create(:user, user_type: :security_bot) }
 
diff --git a/spec/features/users/show_spec.rb b/spec/features/users/show_spec.rb
index 6aeb3023db89129a0dd7e1dede1d37a79f9177e2..a83728007007b213a72ddc8fe755e1bc485bba61 100644
--- a/spec/features/users/show_spec.rb
+++ b/spec/features/users/show_spec.rb
@@ -20,6 +20,8 @@
         expect(page).to have_link('Contributed projects')
         expect(page).to have_link('Personal projects')
         expect(page).to have_link('Snippets')
+        expect(page).to have_link('Followers')
+        expect(page).to have_link('Following')
       end
     end
 
@@ -54,6 +56,50 @@
         expect(page).to have_content('GitLab - work info test')
       end
     end
+
+    context 'follow/unfollow and followers/following' do
+      let_it_be(:followee) { create(:user) }
+      let_it_be(:follower) { create(:user) }
+
+      it 'does not show link to follow' do
+        subject
+
+        expect(page).not_to have_link(text: 'Follow', class: 'gl-button')
+      end
+
+      it 'shows 0 followers and 0 following' do
+        subject
+
+        expect(page).to have_content('0 followers')
+        expect(page).to have_content('0 following')
+      end
+
+      it 'shows 1 followers and 1 following' do
+        follower.follow(user)
+        user.follow(followee)
+
+        subject
+
+        expect(page).to have_content('1 follower')
+        expect(page).to have_content('1 following')
+      end
+
+      it 'does show link to follow' do
+        sign_in(user)
+        visit user_path(followee)
+
+        expect(page).to have_link(text: 'Follow', class: 'gl-button')
+      end
+
+      it 'does show link to unfollow' do
+        sign_in(user)
+        user.follow(followee)
+
+        visit user_path(followee)
+
+        expect(page).to have_link(text: 'Unfollow', class: 'gl-button')
+      end
+    end
   end
 
   context 'with private profile' do
@@ -83,6 +129,8 @@
         expect(page).to have_link('Contributed projects')
         expect(page).to have_link('Personal projects')
         expect(page).to have_link('Snippets')
+        expect(page).to have_link('Followers')
+        expect(page).to have_link('Following')
       end
     end
   end
@@ -242,6 +290,8 @@
           expect(page).not_to have_link('Contributed projects')
           expect(page).not_to have_link('Personal projects')
           expect(page).not_to have_link('Snippets')
+          expect(page).not_to have_link('Followers')
+          expect(page).not_to have_link('Following')
         end
       end
     end
@@ -261,6 +311,8 @@
           expect(page).to have_link('Contributed projects')
           expect(page).to have_link('Personal projects')
           expect(page).to have_link('Snippets')
+          expect(page).to have_link('Followers')
+          expect(page).to have_link('Following')
         end
       end
     end
diff --git a/spec/finders/user_recent_events_finder_spec.rb b/spec/finders/user_recent_events_finder_spec.rb
index afebff5b5c92ae23fd10951e3f6391405f7400c5..5a9243d150d0946819016eca96a72db3d5621673 100644
--- a/spec/finders/user_recent_events_finder_spec.rb
+++ b/spec/finders/user_recent_events_finder_spec.rb
@@ -5,16 +5,17 @@
 RSpec.describe UserRecentEventsFinder do
   let_it_be(:project_owner, reload: true) { create(:user) }
   let_it_be(:current_user, reload: true)  { create(:user) }
-  let(:private_project)  { create(:project, :private, creator: project_owner) }
-  let(:internal_project) { create(:project, :internal, creator: project_owner) }
-  let(:public_project)   { create(:project, :public, creator: project_owner) }
+  let_it_be(:private_project)  { create(:project, :private, creator: project_owner) }
+  let_it_be(:internal_project) { create(:project, :internal, creator: project_owner) }
+  let_it_be(:public_project)   { create(:project, :public, creator: project_owner) }
   let!(:private_event)   { create(:event, project: private_project, author: project_owner) }
   let!(:internal_event)  { create(:event, project: internal_project, author: project_owner) }
   let!(:public_event)    { create(:event, project: public_project, author: project_owner) }
+  let_it_be(:issue) { create(:issue, project: public_project) }
   let(:limit) { nil }
   let(:params) { { limit: limit } }
 
-  subject(:finder) { described_class.new(current_user, project_owner, params) }
+  subject(:finder) { described_class.new(current_user, project_owner, nil, params) }
 
   describe '#execute' do
     context 'when profile is public' do
@@ -39,15 +40,106 @@
       expect(finder.execute).to be_empty
     end
 
-    describe 'design activity events' do
-      let_it_be(:event_a) { create(:design_event, author: project_owner) }
-      let_it_be(:event_b) { create(:design_event, author: project_owner) }
+    context 'events from multiple users' do
+      let_it_be(:second_user, reload: true) { create(:user) }
+      let_it_be(:private_project_second_user) { create(:project, :private, creator: second_user) }
+      let(:internal_project_second_user) { create(:project, :internal, creator: second_user) }
+      let(:public_project_second_user)   { create(:project, :public, creator: second_user) }
+      let!(:private_event_second_user)   { create(:event, project: private_project_second_user, author: second_user) }
+      let!(:internal_event_second_user)  { create(:event, project: internal_project_second_user, author: second_user) }
+      let!(:public_event_second_user)    { create(:event, project: public_project_second_user, author: second_user) }
+
+      it 'includes events from all users', :aggregate_failures do
+        events = described_class.new(current_user, [project_owner, second_user], nil, params).execute
+
+        expect(events).to include(private_event, internal_event, public_event)
+        expect(events).to include(private_event_second_user, internal_event_second_user, public_event_second_user)
+        expect(events.size).to eq(6)
+      end
+
+      it 'does not include events from users with private profile', :aggregate_failures do
+        allow(Ability).to receive(:allowed?).and_call_original
+        allow(Ability).to receive(:allowed?).with(current_user, :read_user_profile, second_user).and_return(false)
+
+        events = described_class.new(current_user, [project_owner, second_user], nil, params).execute
+
+        expect(events).to include(private_event, internal_event, public_event)
+        expect(events.size).to eq(3)
+      end
+    end
+
+    context 'filter activity events' do
+      let!(:push_event) { create(:push_event, project: public_project, author: project_owner) }
+      let!(:merge_event) { create(:event, :merged, project: public_project, author: project_owner) }
+      let!(:issue_event) { create(:event, :closed, project: public_project, target: issue, author: project_owner) }
+      let!(:comment_event) { create(:event, :commented, project: public_project, author: project_owner) }
+      let!(:wiki_event) { create(:wiki_page_event, project: public_project, author: project_owner) }
+      let!(:design_event) { create(:design_event, project: public_project, author: project_owner) }
+      let!(:team_event) { create(:event, :joined, project: public_project, author: project_owner) }
+
+      it 'includes all events', :aggregate_failures do
+        event_filter = EventFilter.new(EventFilter::ALL)
+        events = described_class.new(current_user, project_owner, event_filter, params).execute
+
+        expect(events).to include(private_event, internal_event, public_event)
+        expect(events).to include(push_event, merge_event, issue_event, comment_event, wiki_event, design_event, team_event)
+        expect(events.size).to eq(10)
+      end
+
+      it 'only includes push events', :aggregate_failures do
+        event_filter = EventFilter.new(EventFilter::PUSH)
+        events = described_class.new(current_user, project_owner, event_filter, params).execute
+
+        expect(events).to include(push_event)
+        expect(events.size).to eq(1)
+      end
+
+      it 'only includes merge events', :aggregate_failures do
+        event_filter = EventFilter.new(EventFilter::MERGED)
+        events = described_class.new(current_user, project_owner, event_filter, params).execute
+
+        expect(events).to include(merge_event)
+        expect(events.size).to eq(1)
+      end
+
+      it 'only includes issue events', :aggregate_failures do
+        event_filter = EventFilter.new(EventFilter::ISSUE)
+        events = described_class.new(current_user, project_owner, event_filter, params).execute
+
+        expect(events).to include(issue_event)
+        expect(events.size).to eq(1)
+      end
+
+      it 'only includes comments events', :aggregate_failures do
+        event_filter = EventFilter.new(EventFilter::COMMENTS)
+        events = described_class.new(current_user, project_owner, event_filter, params).execute
+
+        expect(events).to include(comment_event)
+        expect(events.size).to eq(1)
+      end
+
+      it 'only includes wiki events', :aggregate_failures do
+        event_filter = EventFilter.new(EventFilter::WIKI)
+        events = described_class.new(current_user, project_owner, event_filter, params).execute
+
+        expect(events).to include(wiki_event)
+        expect(events.size).to eq(1)
+      end
 
       it 'only includes design events', :aggregate_failures do
-        events = finder.execute
+        event_filter = EventFilter.new(EventFilter::DESIGNS)
+        events = described_class.new(current_user, project_owner, event_filter, params).execute
 
-        expect(events).to include(event_a)
-        expect(events).to include(event_b)
+        expect(events).to include(design_event)
+        expect(events.size).to eq(1)
+      end
+
+      it 'only includes team events', :aggregate_failures do
+        event_filter = EventFilter.new(EventFilter::TEAM)
+        events = described_class.new(current_user, project_owner, event_filter, params).execute
+
+        expect(events).to include(private_event, internal_event, public_event, team_event)
+        expect(events.size).to eq(4)
       end
     end
 
diff --git a/spec/models/user_spec.rb b/spec/models/user_spec.rb
index 2ce6dad1c61a191b74dae29f242f9e4e78b3f91c..860c015e16693956ad085e1c7f96d5acb00ad03a 100644
--- a/spec/models/user_spec.rb
+++ b/spec/models/user_spec.rb
@@ -2831,6 +2831,79 @@
     end
   end
 
+  describe '#following?' do
+    it 'check if following another user' do
+      user = create :user
+      followee1 = create :user
+
+      expect(user.follow(followee1)).to be_truthy
+
+      expect(user.following?(followee1)).to be_truthy
+
+      expect(user.unfollow(followee1)).to be_truthy
+
+      expect(user.following?(followee1)).to be_falsey
+    end
+  end
+
+  describe '#follow' do
+    it 'follow another user' do
+      user = create :user
+      followee1 = create :user
+      followee2 = create :user
+
+      expect(user.followees).to be_empty
+
+      expect(user.follow(followee1)).to be_truthy
+      expect(user.follow(followee1)).to be_falsey
+
+      expect(user.followees).to contain_exactly(followee1)
+
+      expect(user.follow(followee2)).to be_truthy
+      expect(user.follow(followee2)).to be_falsey
+
+      expect(user.followees).to contain_exactly(followee1, followee2)
+    end
+
+    it 'follow itself is not possible' do
+      user = create :user
+
+      expect(user.followees).to be_empty
+
+      expect(user.follow(user)).to be_falsey
+
+      expect(user.followees).to be_empty
+    end
+  end
+
+  describe '#unfollow' do
+    it 'unfollow another user' do
+      user = create :user
+      followee1 = create :user
+      followee2 = create :user
+
+      expect(user.followees).to be_empty
+
+      expect(user.follow(followee1)).to be_truthy
+      expect(user.follow(followee1)).to be_falsey
+
+      expect(user.follow(followee2)).to be_truthy
+      expect(user.follow(followee2)).to be_falsey
+
+      expect(user.followees).to contain_exactly(followee1, followee2)
+
+      expect(user.unfollow(followee1)).to be_truthy
+      expect(user.unfollow(followee1)).to be_falsey
+
+      expect(user.followees).to contain_exactly(followee2)
+
+      expect(user.unfollow(followee2)).to be_truthy
+      expect(user.unfollow(followee2)).to be_falsey
+
+      expect(user.followees).to be_empty
+    end
+  end
+
   describe '.find_by_private_commit_email' do
     context 'with email' do
       let_it_be(:user) { create(:user) }
diff --git a/spec/requests/api/users_spec.rb b/spec/requests/api/users_spec.rb
index bd8e4a59195bad253b8b30d70a69e698d1d544fa..d70a8bd692d936fe58e1141515cbd68c74e78603 100644
--- a/spec/requests/api/users_spec.rb
+++ b/spec/requests/api/users_spec.rb
@@ -652,6 +652,34 @@
         expect(response).to match_response_schema('public_api/v4/user/basic')
         expect(json_response.keys).not_to include 'created_at'
       end
+
+      it "returns the `followers` field for public users" do
+        get api("/users/#{user.id}")
+
+        expect(response).to match_response_schema('public_api/v4/user/basic')
+        expect(json_response.keys).to include 'followers'
+      end
+
+      it "does not return the `followers` field for private users" do
+        get api("/users/#{private_user.id}")
+
+        expect(response).to match_response_schema('public_api/v4/user/basic')
+        expect(json_response.keys).not_to include 'followers'
+      end
+
+      it "returns the `following` field for public users" do
+        get api("/users/#{user.id}")
+
+        expect(response).to match_response_schema('public_api/v4/user/basic')
+        expect(json_response.keys).to include 'following'
+      end
+
+      it "does not return the `following` field for private users" do
+        get api("/users/#{private_user.id}")
+
+        expect(response).to match_response_schema('public_api/v4/user/basic')
+        expect(json_response.keys).not_to include 'following'
+      end
     end
 
     it "returns a 404 error if user id not found" do
@@ -688,6 +716,128 @@
     end
   end
 
+  describe 'POST /users/:id/follow' do
+    let(:followee) { create(:user) }
+
+    context 'on an unfollowed user' do
+      it 'follows the user' do
+        post api("/users/#{followee.id}/follow", user)
+
+        expect(user.followees).to contain_exactly(followee)
+        expect(response).to have_gitlab_http_status(:created)
+      end
+    end
+
+    context 'on a followed user' do
+      before do
+        user.follow(followee)
+      end
+
+      it 'does not change following' do
+        post api("/users/#{followee.id}/follow", user)
+
+        expect(user.followees).to contain_exactly(followee)
+        expect(response).to have_gitlab_http_status(:not_modified)
+      end
+    end
+  end
+
+  describe 'POST /users/:id/unfollow' do
+    let(:followee) { create(:user) }
+
+    context 'on a followed user' do
+      before do
+        user.follow(followee)
+      end
+
+      it 'unfollow the user' do
+        post api("/users/#{followee.id}/unfollow", user)
+
+        expect(user.followees).to be_empty
+        expect(response).to have_gitlab_http_status(:created)
+      end
+    end
+
+    context 'on an unfollowed user' do
+      it 'does not change following' do
+        post api("/users/#{followee.id}/unfollow", user)
+
+        expect(user.followees).to be_empty
+        expect(response).to have_gitlab_http_status(:not_modified)
+      end
+    end
+  end
+
+  describe 'GET /users/:id/followers' do
+    let(:follower) { create(:user) }
+
+    context 'user has followers' do
+      it 'lists followers' do
+        follower.follow(user)
+
+        get api("/users/#{user.id}/followers", user)
+
+        expect(response).to have_gitlab_http_status(:ok)
+        expect(response).to include_pagination_headers
+        expect(json_response).to be_an Array
+      end
+
+      it 'do not lists followers if profile is private' do
+        follower.follow(private_user)
+
+        get api("/users/#{private_user.id}/followers", user)
+
+        expect(response).to have_gitlab_http_status(:not_found)
+        expect(json_response['message']).to eq('404 User Not Found')
+      end
+    end
+
+    context 'user does not have any follower' do
+      it 'does list nothing' do
+        get api("/users/#{user.id}/followers", user)
+
+        expect(response).to have_gitlab_http_status(:ok)
+        expect(response).to include_pagination_headers
+        expect(json_response).to be_empty
+      end
+    end
+  end
+
+  describe 'GET /users/:id/following' do
+    let(:followee) { create(:user) }
+
+    context 'user has followers' do
+      it 'lists following user' do
+        user.follow(followee)
+
+        get api("/users/#{user.id}/following", user)
+
+        expect(response).to have_gitlab_http_status(:ok)
+        expect(response).to include_pagination_headers
+        expect(json_response).to be_an Array
+      end
+
+      it 'do not lists following user if profile is private' do
+        user.follow(private_user)
+
+        get api("/users/#{private_user.id}/following", user)
+
+        expect(response).to have_gitlab_http_status(:not_found)
+        expect(json_response['message']).to eq('404 User Not Found')
+      end
+    end
+
+    context 'user does not have any follower' do
+      it 'does list nothing' do
+        get api("/users/#{user.id}/following", user)
+
+        expect(response).to have_gitlab_http_status(:ok)
+        expect(response).to include_pagination_headers
+        expect(json_response).to be_empty
+      end
+    end
+  end
+
   describe "POST /users" do
     it "creates user" do
       expect do