In this video tutorial, Wes Bos looks into the new context API and the problem that it’s trying to solve:
React 16.3 has a new Context API which makes accessing data and functions anywhere in your application a snap. If you ever find yourself passing data down via props 4-5 levels deep, context might be what you are looking for.
Don’t forget about Neal Fennimore’s recent post on putting things into context. It covers the concept in great detail and provides some workarounds for the quirks you might encounter when using it.