The creators insist React to be the tool for creating interactive UIs. It allows fast and efficient updates, that are able render all the corresponding components throughout all the project. All what’s needed is defining app’s simple states and designing them. It also plays for code structure, makes it more transparent and manageable. They call this feature of React “Declarative”, and along with the next feature it eases up debugging and scalability. also implies similar logic. The next trait – “Component-based” – means you can build complex interactive user interfaces out of “bricks” of encapsulated components, the logic of which is written in JavaScript, rather than templates. Virtual DOM, enabled by the previous, allows actual changes only to be rendered, while pages are treated as fully re-rendered.

JSX, a JavaScript syntax extension incorporating HTML quoting and using HTML tag syntax for subcomponents rendering, is mostly used for the React components.
"Employing the features of ReactJS, our developers create fast and attractive user interfaces of web applications. What is really amazing about ReactJS is that this technology is extremely SEO friendly, which helps us develop websites that are always on the top of the browser search."
React is also compatible with Node.js, thus able to be rendered server-side, there is also a tool React Native, that brings ReactJS to mobile platforms.
React is BSD licensed and there is constant work on optimizing it, making it work quicker and be more usable.