React, Flux, GraphQL, Hack, HHVM...? All of this and more!
GraphQL is a technology for one of the most common things developers working with external data: Fetching and manipulating data on a remote server. It is similar to REST, but is more straightforward and a standard where as REST is just a vague term.
GraphQL is superb in it's simplicity for data fetching. You simply write a query in a JSON format and you get the result back in the corresponding load of data back replicating the query structure itself.
This makes using GraphQL across server implementations very simple. This is probably the number one reason why GraphQL is gaining speed rapidly. In just under a year since opening up the spec, this Facebook technology is spreading everywhere like React has in it's existance.