HTTP/2

What is HTTP/2 and Why

HTTP/1.1 has been serving most part of the Web since 1997. As websites get more and more sophisticated and resource intensive, it starts to show its limitations, e.g. one outstanding request per TCP connection. So its next-generation emerged: HTTP/2.

HTTP/2 FAQ does a great job explaining the background and specifications. Highly recommended. Here is an executive summary, HTTP/2:

• is specifically designed to improve performance
• is based on SPDY
• is binary, instead of textual
• is fully multiplexed, instead of ordered and blocking
• can therefore use one connection for parallelism
• uses header compression to reduce overhead
• allows servers to push responses proactively into client caches
• is backward-compatible, designed to be drop-in replacement for HTTP/1.1
• is supported by most broswers over TLS

HttpWatch reported good performance improvement by using HTTP/2.