<p>##What problem faced by fb that they created ReactJS?</p>
<ul>
<li>Updating the UI with rapidly changing data  .</li>
</ul>
<p>The key features of React are:</p>
<ul>
<li>Component-based: Components are the smallest unit in a React application. Anything that we want to render is rendered through components. Components help in maintainability and </li>
<li>Virtual DOM: React uses virtual DOM concept for DOM manipulation which improves the performance of the application</li>
<li>Unidirectional data flow:  React’s one-way data flow (also called one-way binding) keeps everything modular and fast and easy for debugging.</li>
<li>JSX syntax: React used JSX syntax which is similar to XML and HTML syntax which makes it easy for writing markup and binding events in components </li>
<li>SEO performance: The SEO performance can be improved using the server-side rendering concept. We can develop isomorphic applications using React which increases the SEO performance.</li>
</ul>


##What problem faced by fb that they created ReactJS?
 - Updating the UI with rapidly changing data  .

The key features of React are:

- Component-based: Components are the smallest unit in a React application. Anything that we want to render is rendered through components. Components help in maintainability and 
- Virtual DOM: React uses virtual DOM concept for DOM manipulation which improves the performance of the application
- Unidirectional data flow:  React’s one-way data flow (also called one-way binding) keeps everything modular and fast and easy for debugging.
- JSX syntax: React used JSX syntax which is similar to XML and HTML syntax which makes it easy for writing markup and binding events in components 
- SEO performance: The SEO performance can be improved using the server-side rendering concept. We can develop isomorphic applications using React which increases the SEO performance.
 

Why React?