React has always provided a context API for developers, but it was always considered experimental. Context is an alternative approach to passing data from one component to the next. For example, using properties, you can pass data through a tree of components that is several layers deep. The components in the middle of this tree don't actually use any of these properties—they're just acting as intermediaries. This becomes problematic as your application grows because you have lots of props in your source that add to the complexity.

The new context API in React 16.3 is more official and provides a way for you to supply your components with data at any tree level. You can read more about the new context API here: https://reactjs.org/docs/context.html.