diff --git a/src/App.scss b/src/App.scss
index 695435da4..a2fd3ddf9 100644
--- a/src/App.scss
+++ b/src/App.scss
@@ -21,3 +21,7 @@
 .message-body {
   white-space: pre-line;
 }
+
+iframe {
+  display: none;
+}
diff --git a/src/App.tsx b/src/App.tsx
index db56b44b0..c2cfbfe54 100644
--- a/src/App.tsx
+++ b/src/App.tsx
@@ -1,15 +1,30 @@
-import React from 'react';
-import 'bulma/bulma.sass';
+/* eslint-disable max-len */
 import '@fortawesome/fontawesome-free/css/all.css';
+import 'bulma/bulma.sass';
+import React from 'react';
 import './App.scss';
 
 import classNames from 'classnames';
-import { PostsList } from './components/PostsList';
+import { Loader } from './components/Loader';
 import { PostDetails } from './components/PostDetails';
+import { PostsList } from './components/PostsList';
 import { UserSelector } from './components/UserSelector';
-import { Loader } from './components/Loader';
+import { usePostsContext } from './hooks/usePostsContext';
+import { useUserContext } from './hooks/useUserContext';
 
 export const App: React.FC = () => {
+  const {
+    posts,
+    isPostsError,
+    isPostsPending,
+    selectedPost,
+  } = usePostsContext();
+  const { selectedUser } = useUserContext();
+
+  const hasError = !isPostsPending && isPostsError;
+  const withoutErrors = selectedUser && !isPostsError;
+  const fetchedWithoutErrors = withoutErrors && !isPostsPending;
+
   return (
     <main className="section">
       <div className="container">
@@ -21,24 +36,28 @@ export const App: React.FC = () => {
               </div>
 
               <div className="block" data-cy="MainContent">
-                <p data-cy="NoSelectedUser">
-                  No user selected
-                </p>
-
-                <Loader />
-
-                <div
-                  className="notification is-danger"
-                  data-cy="PostsLoadingError"
-                >
-                  Something went wrong!
-                </div>
-
-                <div className="notification is-warning" data-cy="NoPostsYet">
-                  No posts yet
-                </div>
-
-                <PostsList />
+                {!selectedUser && (
+                  <p data-cy="NoSelectedUser">
+                    No user selected
+                  </p>
+                )}
+                {withoutErrors && isPostsPending && (<Loader />)}
+                {fetchedWithoutErrors && (posts.length > 0
+                  ? <PostsList />
+                  : (
+                    <div className="notification is-warning" data-cy="NoPostsYet">
+                      No posts yet
+                    </div>
+                  )
+                )}
+                {hasError && (
+                  <div
+                    className="notification is-danger"
+                    data-cy="PostsLoadingError"
+                  >
+                    Something went wrong!
+                  </div>
+                )}
               </div>
             </div>
           </div>
@@ -50,11 +69,13 @@ export const App: React.FC = () => {
               'is-parent',
               'is-8-desktop',
               'Sidebar',
-              'Sidebar--open',
+              {
+                'Sidebar--open': selectedPost,
+              },
             )}
           >
             <div className="tile is-child box is-success ">
-              <PostDetails />
+              {selectedPost && <PostDetails />}
             </div>
           </div>
         </div>
diff --git a/src/Root.tsx b/src/Root.tsx
new file mode 100644
index 000000000..facd994c3
--- /dev/null
+++ b/src/Root.tsx
@@ -0,0 +1,16 @@
+import { App } from './App';
+import { CommentsContextProvider } from './context/CommentsContext';
+import { PostsContextProvider } from './context/PostsContext';
+import { UserContextProvider } from './context/UserContext';
+
+const Root: React.FC = () => (
+  <UserContextProvider>
+    <PostsContextProvider>
+      <CommentsContextProvider>
+        <App />
+      </CommentsContextProvider>
+    </PostsContextProvider>
+  </UserContextProvider>
+);
+
+export default Root;
diff --git a/src/components/NewCommentForm.tsx b/src/components/NewCommentForm.tsx
index 73a8a0b45..314b50881 100644
--- a/src/components/NewCommentForm.tsx
+++ b/src/components/NewCommentForm.tsx
@@ -1,8 +1,67 @@
-import React from 'react';
+import classNames from 'classnames';
+import React, { useState } from 'react';
+import { useCommentsContext } from '../hooks/useCommentsContext';
+
+const initialDetails = {
+  name: '',
+  email: '',
+  body: '',
+};
 
 export const NewCommentForm: React.FC = () => {
+  const { addingComment, handleAddComment } = useCommentsContext();
+  const [commentDetails, setCommentDetails] = useState(initialDetails);
+  const [nameError, setNameError] = useState(false);
+  const [emailError, setEmailError] = useState(false);
+  const [bodyError, setBodyError] = useState(false);
+
+  const handleResetForm = () => {
+    setNameError(false);
+    setEmailError(false);
+    setBodyError(false);
+    setCommentDetails(prev => ({
+      ...prev,
+      body: '',
+    }));
+  };
+
+  const handleSubmitForm = (event: React.FormEvent) => {
+    event.preventDefault();
+
+    if (!commentDetails.name) {
+      setNameError(true);
+    }
+
+    if (!commentDetails.email) {
+      setEmailError(true);
+    }
+
+    if (!commentDetails.body) {
+      setBodyError(true);
+    }
+
+    if (commentDetails.name
+      && commentDetails.email
+      && commentDetails.body
+    ) {
+      handleAddComment(commentDetails);
+      handleResetForm();
+    }
+  };
+
+  const handleDetailsChange = (fieldName: string, value: string) => {
+    setCommentDetails(prev => ({
+      ...prev,
+      [fieldName]: value,
+    }));
+  };
+
   return (
-    <form data-cy="NewCommentForm">
+    <form
+      data-cy="NewCommentForm"
+      onReset={handleResetForm}
+      onSubmit={handleSubmitForm}
+    >
       <div className="field" data-cy="NameField">
         <label className="label" htmlFor="comment-author-name">
           Author Name
@@ -14,24 +73,32 @@ export const NewCommentForm: React.FC = () => {
             name="name"
             id="comment-author-name"
             placeholder="Name Surname"
-            className="input is-danger"
+            className={classNames('input', {
+              'is-danger': nameError,
+            })}
+            value={commentDetails.name}
+            onChange={e => handleDetailsChange(e.target.name, e.target.value)}
           />
 
           <span className="icon is-small is-left">
             <i className="fas fa-user" />
           </span>
 
-          <span
-            className="icon is-small is-right has-text-danger"
-            data-cy="ErrorIcon"
-          >
-            <i className="fas fa-exclamation-triangle" />
-          </span>
+          {nameError && (
+            <span
+              className="icon is-small is-right has-text-danger"
+              data-cy="ErrorIcon"
+            >
+              <i className="fas fa-exclamation-triangle" />
+            </span>
+          )}
         </div>
 
-        <p className="help is-danger" data-cy="ErrorMessage">
-          Name is required
-        </p>
+        {nameError && (
+          <p className="help is-danger" data-cy="ErrorMessage">
+            Name is required
+          </p>
+        )}
       </div>
 
       <div className="field" data-cy="EmailField">
@@ -45,24 +112,32 @@ export const NewCommentForm: React.FC = () => {
             name="email"
             id="comment-author-email"
             placeholder="email@test.com"
-            className="input is-danger"
+            className={classNames('input', {
+              'is-danger': emailError,
+            })}
+            value={commentDetails.email}
+            onChange={e => handleDetailsChange(e.target.name, e.target.value)}
           />
 
           <span className="icon is-small is-left">
             <i className="fas fa-envelope" />
           </span>
 
-          <span
-            className="icon is-small is-right has-text-danger"
-            data-cy="ErrorIcon"
-          >
-            <i className="fas fa-exclamation-triangle" />
-          </span>
+          {emailError && (
+            <span
+              className="icon is-small is-right has-text-danger"
+              data-cy="ErrorIcon"
+            >
+              <i className="fas fa-exclamation-triangle" />
+            </span>
+          )}
         </div>
 
-        <p className="help is-danger" data-cy="ErrorMessage">
-          Email is required
-        </p>
+        {emailError && (
+          <p className="help is-danger" data-cy="ErrorMessage">
+            Email is required
+          </p>
+        )}
       </div>
 
       <div className="field" data-cy="BodyField">
@@ -75,25 +150,39 @@ export const NewCommentForm: React.FC = () => {
             id="comment-body"
             name="body"
             placeholder="Type comment here"
-            className="textarea is-danger"
+            className={classNames('textarea', {
+              'is-danger': bodyError,
+            })}
+            value={commentDetails.body}
+            onChange={e => handleDetailsChange(e.target.name, e.target.value)}
           />
         </div>
 
-        <p className="help is-danger" data-cy="ErrorMessage">
-          Enter some text
-        </p>
+        {bodyError && (
+          <p className="help is-danger" data-cy="ErrorMessage">
+            Enter some text
+          </p>
+        )}
       </div>
 
       <div className="field is-grouped">
         <div className="control">
-          <button type="submit" className="button is-link is-loading">
+          <button
+            type="submit"
+            className={classNames('button is-link', {
+              'is-loading': addingComment,
+            })}
+          >
             Add
           </button>
         </div>
 
         <div className="control">
           {/* eslint-disable-next-line react/button-has-type */}
-          <button type="reset" className="button is-link is-light">
+          <button
+            type="reset"
+            className="button is-link is-light"
+          >
             Clear
           </button>
         </div>
diff --git a/src/components/PostDetails.tsx b/src/components/PostDetails.tsx
index ace945f0a..7c69548db 100644
--- a/src/components/PostDetails.tsx
+++ b/src/components/PostDetails.tsx
@@ -1,118 +1,107 @@
-import React from 'react';
+/* eslint-disable react/jsx-one-expression-per-line */
+import React, { useEffect, useState } from 'react';
+import { useCommentsContext } from '../hooks/useCommentsContext';
+import { usePostsContext } from '../hooks/usePostsContext';
 import { Loader } from './Loader';
 import { NewCommentForm } from './NewCommentForm';
 
 export const PostDetails: React.FC = () => {
+  const { selectedPost } = usePostsContext();
+  const {
+    comments,
+    isCommentsError,
+    isCommentsPending,
+    handleDeleteComment,
+  } = useCommentsContext();
+
+  const [addPost, setAddPost] = useState(false);
+
+  const hasError = isCommentsError && !isCommentsPending;
+  const withoutError = selectedPost && !isCommentsError;
+  const pending = withoutError && isCommentsPending;
+  const fetched = withoutError && !isCommentsPending;
+
+  useEffect(() => {
+    setAddPost(false);
+  }, [selectedPost]);
+
   return (
     <div className="content" data-cy="PostDetails">
-      <div className="content" data-cy="PostDetails">
-        <div className="block">
-          <h2 data-cy="PostTitle">
-            #18: voluptate et itaque vero tempora molestiae
-          </h2>
+      <div className="block">
+        <h2 data-cy="PostTitle">
+          #{selectedPost?.id}: {selectedPost?.title}
+        </h2>
 
-          <p data-cy="PostBody">
-            eveniet quo quis
-            laborum totam consequatur non dolor
-            ut et est repudiandae
-            est voluptatem vel debitis et magnam
-          </p>
-        </div>
-
-        <div className="block">
-          <Loader />
+        <p data-cy="PostBody">
+          {selectedPost?.body}
+        </p>
+      </div>
 
+      <div className="block">
+        {pending && <Loader />}
+        {hasError && (
           <div className="notification is-danger" data-cy="CommentsError">
             Something went wrong
           </div>
+        )}
+        {fetched && (
+          <>
+            {comments.length > 0
+              ? (
+                <>
+                  <p className="title is-4">Comments:</p>
+                  {comments.map(comment => (
+                    <article
+                      className="message is-small"
+                      data-cy="Comment"
+                      key={comment.id}
+                    >
+                      <div className="message-header">
+                        <a
+                          href={`mailto:${comment.email}`}
+                          data-cy="CommentAuthor"
+                        >
+                          {comment.name}
+                        </a>
 
-          <p className="title is-4" data-cy="NoCommentsMessage">
-            No comments yet
-          </p>
-
-          <p className="title is-4">Comments:</p>
-
-          <article className="message is-small" data-cy="Comment">
-            <div className="message-header">
-              <a href="mailto:misha@mate.academy" data-cy="CommentAuthor">
-                Misha Hrynko
-              </a>
-              <button
-                data-cy="CommentDelete"
-                type="button"
-                className="delete is-small"
-                aria-label="delete"
-              >
-                delete button
-              </button>
-            </div>
-
-            <div className="message-body" data-cy="CommentBody">
-              Some comment
-            </div>
-          </article>
-
-          <article className="message is-small" data-cy="Comment">
-            <div className="message-header">
-              <a
-                href="mailto:misha@mate.academy"
-                data-cy="CommentAuthor"
-              >
-                Misha Hrynko
-              </a>
+                        <button
+                          data-cy="CommentDelete"
+                          type="button"
+                          className="delete is-small"
+                          aria-label="delete"
+                          onClick={() => handleDeleteComment(comment.id)}
+                        >
+                          delete button
+                        </button>
+                      </div>
 
+                      <div className="message-body" data-cy="CommentBody">
+                        {comment.body}
+                      </div>
+                    </article>
+                  ))}
+                </>
+              )
+              : (
+                <p className="title is-4" data-cy="NoCommentsMessage">
+                  No comments yet
+                </p>
+              )}
+            {!addPost && (
               <button
-                data-cy="CommentDelete"
+                data-cy="WriteCommentButton"
                 type="button"
-                className="delete is-small"
-                aria-label="delete"
+                className="button is-link"
+                onClick={() => setAddPost(true)}
               >
-                delete button
+                Write a comment
               </button>
-            </div>
-            <div
-              className="message-body"
-              data-cy="CommentBody"
-            >
-              One more comment
-            </div>
-          </article>
-
-          <article className="message is-small" data-cy="Comment">
-            <div className="message-header">
-              <a
-                href="mailto:misha@mate.academy"
-                data-cy="CommentAuthor"
-              >
-                Misha Hrynko
-              </a>
-
-              <button
-                data-cy="CommentDelete"
-                type="button"
-                className="delete is-small"
-                aria-label="delete"
-              >
-                delete button
-              </button>
-            </div>
-
-            <div className="message-body" data-cy="CommentBody">
-              {'Multi\nline\ncomment'}
-            </div>
-          </article>
-
-          <button
-            data-cy="WriteCommentButton"
-            type="button"
-            className="button is-link"
-          >
-            Write a comment
-          </button>
-        </div>
-
-        <NewCommentForm />
+            )}
+          </>
+        )}
       </div>
+
+      {addPost && <NewCommentForm />}
     </div>
   );
 };
diff --git a/src/components/PostsList.tsx b/src/components/PostsList.tsx
index 6e6efc0f3..cc9dece6c 100644
--- a/src/components/PostsList.tsx
+++ b/src/components/PostsList.tsx
@@ -1,85 +1,50 @@
+import classNames from 'classnames';
 import React from 'react';
-
-export const PostsList: React.FC = () => (
-  <div data-cy="PostsList">
-    <p className="title">Posts:</p>
-
-    <table className="table is-fullwidth is-striped is-hoverable is-narrow">
-      <thead>
-        <tr className="has-background-link-light">
-          <th>#</th>
-          <th>Title</th>
-          <th> </th>
-        </tr>
-      </thead>
-
-      <tbody>
-        <tr data-cy="Post">
-          <td data-cy="PostId">17</td>
-
-          <td data-cy="PostTitle">
-            fugit voluptas sed molestias voluptatem provident
-          </td>
-
-          <td className="has-text-right is-vcentered">
-            <button
-              type="button"
-              data-cy="PostButton"
-              className="button is-link is-light"
-            >
-              Open
-            </button>
-          </td>
-        </tr>
-
-        <tr data-cy="Post">
-          <td data-cy="PostId">18</td>
-
-          <td data-cy="PostTitle">
-            voluptate et itaque vero tempora molestiae
-          </td>
-
-          <td className="has-text-right is-vcentered">
-            <button
-              type="button"
-              data-cy="PostButton"
-              className="button is-link"
-            >
-              Close
-            </button>
-          </td>
-        </tr>
-
-        <tr data-cy="Post">
-          <td data-cy="PostId">19</td>
-          <td data-cy="PostTitle">adipisci placeat illum aut reiciendis qui</td>
-
-          <td className="has-text-right is-vcentered">
-            <button
-              type="button"
-              data-cy="PostButton"
-              className="button is-link is-light"
-            >
-              Open
-            </button>
-          </td>
-        </tr>
-
-        <tr data-cy="Post">
-          <td data-cy="PostId">20</td>
-          <td data-cy="PostTitle">doloribus ad provident suscipit at</td>
-
-          <td className="has-text-right is-vcentered">
-            <button
-              type="button"
-              data-cy="PostButton"
-              className="button is-link is-light"
-            >
-              Open
-            </button>
-          </td>
-        </tr>
-      </tbody>
-    </table>
-  </div>
-);
+import { usePostsContext } from '../hooks/usePostsContext';
+
+export const PostsList: React.FC = () => {
+  const { posts, selectedPost, handleSelectPost } = usePostsContext();
+
+  return (
+    <div data-cy="PostsList">
+      <p className="title">Posts:</p>
+
+      <table className="table is-fullwidth is-striped is-hoverable is-narrow">
+        <thead>
+          <tr className="has-background-link-light">
+            <th>#</th>
+            <th>Title</th>
+            <th> </th>
+          </tr>
+        </thead>
+
+        <tbody>
+          {posts.map(post => (
+            <tr data-cy="Post" key={post.id}>
+              <td data-cy="PostId">{post.id}</td>
+
+              <td data-cy="PostTitle">
+                {post.title}
+              </td>
+
+              <td className="has-text-right is-vcentered">
+                <button
+                  type="button"
+                  data-cy="PostButton"
+                  className={classNames('button is-link', {
+                    'is-light': selectedPost?.id !== post.id,
+                  })}
+                  onClick={() => handleSelectPost(post)}
+                >
+                  {selectedPost?.id === post.id
+                    ? 'Close'
+                    : 'Open'}
+                </button>
+              </td>
+            </tr>
+          ))}
+        </tbody>
+      </table>
+    </div>
+  );
+};
diff --git a/src/components/UserSelector.tsx b/src/components/UserSelector.tsx
index cb83a8f68..f5a431cde 100644
--- a/src/components/UserSelector.tsx
+++ b/src/components/UserSelector.tsx
@@ -1,10 +1,39 @@
-import React from 'react';
+import classNames from 'classnames';
+import React, { useEffect, useRef, useState } from 'react';
+import { useUserContext } from '../hooks/useUserContext';
+import { User } from '../types/User';
 
 export const UserSelector: React.FC = () => {
+  const {
+    users,
+    onSelect,
+    selectedUser,
+  } = useUserContext();
+  const [showDropdown, setShowDropdown] = useState(false);
+  const dropdownRef = useRef<HTMLDivElement>(null);
+
+  const handleSelectUser = (user: User) => {
+    setShowDropdown(false);
+    onSelect(user);
+  };
+
+  useEffect(() => {
+    const closeDropdown = (event: MouseEvent) => {
+      if (!dropdownRef.current?.contains(event.target as Node)) {
+        setShowDropdown(false);
+      }
+    };
+
+    window.addEventListener('click', closeDropdown);
+  }, []);
+
   return (
     <div
       data-cy="UserSelector"
-      className="dropdown is-active"
+      className={classNames('dropdown', {
+        'is-active': showDropdown,
+      })}
+      ref={dropdownRef}
     >
       <div className="dropdown-trigger">
         <button
@@ -12,8 +41,13 @@ export const UserSelector: React.FC = () => {
           className="button"
           aria-haspopup="true"
           aria-controls="dropdown-menu"
+          onClick={() => setShowDropdown(prev => !prev)}
         >
-          <span>Choose a user</span>
+          <span>
+            {selectedUser
+              ? selectedUser.name
+              : 'Choose a user'}
+          </span>
 
           <span className="icon is-small">
             <i className="fas fa-angle-down" aria-hidden="true" />
@@ -23,11 +57,18 @@ export const UserSelector: React.FC = () => {
 
       <div className="dropdown-menu" id="dropdown-menu" role="menu">
         <div className="dropdown-content">
-          <a href="#user-1" className="dropdown-item">Leanne Graham</a>
-          <a href="#user-2" className="dropdown-item is-active">Ervin Howell</a>
-          <a href="#user-3" className="dropdown-item">Clementine Bauch</a>
-          <a href="#user-4" className="dropdown-item">Patricia Lebsack</a>
-          <a href="#user-5" className="dropdown-item">Chelsey Dietrich</a>
+          {users.map(user => (
+            <a
+              key={user.id}
+              href={`#user-${user.id}`}
+              className={classNames('dropdown-item', {
+                'is-active': selectedUser?.id === user.id,
+              })}
+              onClick={() => handleSelectUser(user)}
+            >
+              {user.name}
+            </a>
+          ))}
         </div>
       </div>
     </div>
diff --git a/src/context/CommentsContext.tsx b/src/context/CommentsContext.tsx
new file mode 100644
index 000000000..efd14e2eb
--- /dev/null
+++ b/src/context/CommentsContext.tsx
@@ -0,0 +1,116 @@
+import {
+  createContext, useEffect, useMemo, useState,
+} from 'react';
+import { Comment, CommentData } from '../types/Comment';
+import { usePostsContext } from '../hooks/usePostsContext';
+import { client } from '../utils/fetchClient';
+import { Error } from '../types/Error';
+
+export interface ProvidedValue {
+  comments: Comment[],
+  isCommentsPending: boolean,
+  isCommentsError: boolean,
+  addingComment: boolean,
+  handleDeleteComment: (commentId: number) => Promise<void>,
+  handleAddComment: (data: CommentData) => Promise<void>,
+}
+
+type Props = {
+  children: React.ReactNode,
+};
+
+export const CommentsContext = createContext({} as ProvidedValue);
+
+export const CommentsContextProvider = ({ children }: Props) => {
+  const { selectedPost } = usePostsContext();
+  const [comments, setComments] = useState<Comment[]>([]);
+  const [isCommentsPending, setIsCommentsPending] = useState(false);
+  const [isCommentsError, setIsCommentsError] = useState(false);
+  const [addingComment, setAddingComment] = useState(false);
+
+  const fetchPostComments = async () => {
+    setIsCommentsPending(true);
+    setIsCommentsError(false);
+    if (selectedPost !== null) {
+      try {
+        const postComments = await client.get<Comment[] | Error>(`/comments?postId=${selectedPost.id}`);
+
+        if ((postComments as Error).error) {
+          setIsCommentsError(true);
+        } else {
+          setComments(postComments as Comment[]);
+        }
+      } catch (error) {
+        setIsCommentsError(true);
+      } finally {
+        setIsCommentsPending(false);
+      }
+    }
+  };
+
+  const handleDeleteComment = async (commentId: number) => {
+    try {
+      setComments((prevComments) => (
+        prevComments.filter(({ id }) => id !== commentId)));
+      const response = await client.delete(`/comments/${commentId}`) as Comment | Error;
+
+      if ((response as Error).statusCode === 500) {
+        setIsCommentsError(true);
+        setComments(comments);
+      }
+    } catch (error) {
+      setIsCommentsError(true);
+    }
+  };
+
+  const handleAddComment = async (data: CommentData) => {
+    setAddingComment(true);
+    try {
+      const newComment = {
+        postId: selectedPost?.id,
+        name: data.name,
+        email: data.email,
+        body: data.body,
+      };
+
+      const res = await client.post('/comments', newComment) as Comment | Error;
+
+      if ((res as Error).error) {
+        setIsCommentsError(true);
+      } else {
+        setComments(prev => ([
+          ...prev,
+          res as Comment,
+        ]));
+      }
+    } catch (error) {
+      setIsCommentsError(true);
+    } finally {
+      setAddingComment(false);
+    }
+  };
+
+  useEffect(() => {
+    fetchPostComments();
+  }, [selectedPost]);
+
+  const providedValue = useMemo(() => ({
+    comments,
+    isCommentsPending,
+    isCommentsError,
+    addingComment,
+    handleDeleteComment,
+    handleAddComment,
+  }), [
+    comments,
+    isCommentsPending,
+    isCommentsError,
+    addingComment,
+  ]);
+
+  return (
+    <CommentsContext.Provider value={providedValue}>
+      {children}
+    </CommentsContext.Provider>
+  );
+};
diff --git a/src/context/PostsContext.tsx b/src/context/PostsContext.tsx
new file mode 100644
index 000000000..6700657ec
--- /dev/null
+++ b/src/context/PostsContext.tsx
@@ -0,0 +1,82 @@
+import {
+  createContext,
+  useEffect,
+  useMemo,
+  useState,
+} from 'react';
+import { useUserContext } from '../hooks/useUserContext';
+import { Error } from '../types/Error';
+import { Post } from '../types/Post';
+import { client } from '../utils/fetchClient';
+
+export interface ProvidedValue {
+  posts: Post[],
+  selectedPost: Post | null,
+  isPostsPending: boolean,
+  isPostsError: boolean,
+  handleSelectPost: (post: Post) => void
+}
+
+type Props = {
+  children: React.ReactNode,
+};
+
+export const PostsContext = createContext({} as ProvidedValue);
+
+export const PostsContextProvider = ({ children }: Props) => {
+  const { selectedUser } = useUserContext();
+  const [isPostsPending, setIsPostsPending] = useState(false);
+  const [isPostsError, setIsPostsError] = useState(false);
+  const [posts, setPosts] = useState<Post[]>([]);
+  const [selectedPost, setSelectedPost] = useState<Post | null>(null);
+
+  const fetchUserPosts = async () => {
+    setIsPostsPending(true);
+    setIsPostsError(false);
+    setSelectedPost(null);
+    if (selectedUser !== null) {
+      try {
+        const userPosts = await client.get<Post[] | Error>(`/posts?userId=${selectedUser?.id}`);
+
+        if ((userPosts as Error).error) {
+          setIsPostsError(true);
+        } else {
+          setPosts(userPosts as Post[]);
+        }
+      } catch (error) {
+        setIsPostsError(true);
+      } finally {
+        setIsPostsPending(false);
+      }
+    }
+  };
+
+  const handleSelectPost = (post: Post) => {
+    if (selectedPost?.id === post.id) {
+      setSelectedPost(null);
+    } else {
+      setSelectedPost(post);
+    }
+  };
+
+  useEffect(() => {
+    fetchUserPosts();
+  }, [selectedUser]);
+
+  const providedValue = useMemo(() => ({
+    posts,
+    selectedPost,
+    isPostsPending,
+    isPostsError,
+    handleSelectPost,
+  }), [posts,
+    selectedPost,
+    isPostsPending,
+    isPostsError]);
+
+  return (
+    <PostsContext.Provider value={providedValue}>
+      {children}
+    </PostsContext.Provider>
+  );
+};
diff --git a/src/context/UserContext.tsx b/src/context/UserContext.tsx
new file mode 100644
index 000000000..8e7a78ae6
--- /dev/null
+++ b/src/context/UserContext.tsx
@@ -0,0 +1,46 @@
+import {
+  createContext,
+  useEffect,
+  useMemo,
+  useState,
+} from 'react';
+import { User } from '../types/User';
+import { client } from '../utils/fetchClient';
+
+export interface ProvidedValue {
+  users: User[]
+  selectedUser: User | null,
+  onSelect: (user: User) => void,
+}
+
+type Props = {
+  children: React.ReactNode
+};
+
+export const UserContext = createContext({} as ProvidedValue);
+
+export const UserContextProvider = ({ children }: Props) => {
+  const [users, setUsers] = useState<User[]>([]);
+  const [selectedUser, setSelectedUser] = useState<User | null>(null);
+
+  useEffect(() => {
+    client.get<User[]>('/users')
+      .then((res) => setUsers(res));
+  }, []);
+
+  const onSelect = (user: User) => {
+    setSelectedUser(user);
+  };
+
+  const providedValue = useMemo(() => ({
+    users,
+    selectedUser,
+    onSelect,
+  }), [users, selectedUser]);
+
+  return (
+    <UserContext.Provider value={providedValue}>
+      {children}
+    </UserContext.Provider>
+  );
+};
diff --git a/src/hooks/useCommentsContext.ts b/src/hooks/useCommentsContext.ts
new file mode 100644
index 000000000..4a9b90b8e
--- /dev/null
+++ b/src/hooks/useCommentsContext.ts
@@ -0,0 +1,6 @@
+import { useContext } from 'react';
+import { CommentsContext } from '../context/CommentsContext';
+
+export const useCommentsContext = () => {
+  return useContext(CommentsContext);
+};
diff --git a/src/hooks/usePostsContext.ts b/src/hooks/usePostsContext.ts
new file mode 100644
index 000000000..a34ed3d88
--- /dev/null
+++ b/src/hooks/usePostsContext.ts
@@ -0,0 +1,6 @@
+import { useContext } from 'react';
+import { PostsContext } from '../context/PostsContext';
+
+export const usePostsContext = () => {
+  return useContext(PostsContext);
+};
diff --git a/src/hooks/useUserContext.ts b/src/hooks/useUserContext.ts
new file mode 100644
index 000000000..3e457e51d
--- /dev/null
+++ b/src/hooks/useUserContext.ts
@@ -0,0 +1,6 @@
+import { useContext } from 'react';
+import { UserContext } from '../context/UserContext';
+
+export const useUserContext = () => {
+  return useContext(UserContext);
+};
diff --git a/src/index.tsx b/src/index.tsx
index 6710ea0c2..aa89e5933 100644
--- a/src/index.tsx
+++ b/src/index.tsx
@@ -1,8 +1,7 @@
 import ReactDOM from 'react-dom';
-
-import { App } from './App';
+import Root from './Root';
 
 ReactDOM.render(
-  <App />,
+  <Root />,
   document.getElementById('root'),
 );
diff --git a/src/types/Error.ts b/src/types/Error.ts
new file mode 100644
index 000000000..7ae589803
--- /dev/null
+++ b/src/types/Error.ts
@@ -0,0 +1,5 @@
+export interface Error {
+  error: string,
+  message: string,
+  statusCode: number,
+}