SPDY's multiplexed streams feature allowed for mapping multiple requests to multiple streams on a single connection. These streams were bidirectional and could be initiated by either the client or the server (the server push feature). Opening multiple streams over one single connection made it possible to avoid the overhead of establishing a new connection on each client/server exchange, especially when downloading multiple resources in parallel to complete the rendering of a single page. Thus, this first feature made it possible to get rid of the limited number of possible connections when using the HTTP/1 protocol:
How multiplexed and prioritized streams work
Moreover, SPDY's streams were prioritized. ...
