What is React?

React is a library built by Facebook for building UIs with components. The idea with components is that implementation details can be abstracted away into manageable chunks that can be more-easily reasoned about. Additionally, composing these abstractions becomes a powerful programming tool.

Quick aside: you'll soon learn that in the React community the term "reason about" must be used at least 12 times in any documentation in order for it to gain acceptance. 😎

Consider the following example with the <video> element:

Notice how we don't have a bunch of <div> elements with a bunch of attributes for things like data-bind="some-binding: {something: someObservable() != something()}". Instead, we have just <video>. This is the elegance and power of components.