SPDY is a new web protocol developed by Google that will help to browse the Web faster (even 50%). It's pronounced as "speedy". It is not meant to replace HTTP,  but
to augment HTTP. The new protocol incorporates features like
multiplexed streams, request prioritization and HTTP header compression.

Here are SPDY improvements over HTTP:

  • Multiplexed requests. There is no limit to the number of
    requests that can be issued concurrently over a single SPDY connection. 
    Because requests are interleaved on a single channel, the efficiency of
    TCP is much higher.
  • Prioritized requests. Clients can request certain resources to
    be delivered first.  This avoids the problem of congesting the network
    channel with non-critical resources when a high-priority request is
  • Compressed headers.  Clients today send a significant amount of
    redundant data in the form of HTTP headers.  Because a single Web page
    may require 50 or 100 sub requests, this data is significant. Compressing
    the headers saves a significant amount of latency and bandwidth
    compared to HTTP.

Google has released an prototype webserver implementing SPDY as open source. Also SPDY already comes built-in in Google Chrome, other browsers and webservers don't support it yet, however if this becomes main stream more browsers will support it.