> Braid-HTTP is an extension to HTTP that generalizes it from a state transfer to a state synchronization protocol.
They could simply say it's a synchronization protocol over HTTP.
The HTTP acronym stands for HyperText Transfer Protocol. ReST stands for Representational State Transfer.
HTTP began as a HTML Transfer Protocol, but then generalized to content-types beyond HTML, such as images, scripts -- and general state. So today HTTP is known as a State Transfer Protocol. This architecture was canonicalized as ReST in Roy Fielding's dissertation.
In order to generalize HTTP from State Transfer to State Synchronization, we have to augment some parts of it, such as request/response. Instead of just getting a single response to a request, Braid allows a client to subscribe to a resource, with a single request which will be then given multiple responses -- one response for each update to the resource.
It is quite elegant to extend HTTP at this level! And we can do so without requiring any changes to web browsers.