Firefox 36 arrives with full HTTP/2 support and a new design for Android tablets. Mozilla launched Firefox 36 for Windows, Mac, Linux, and Android. The biggest news for the browser is undoubtedly HTTP/2 support. HTTP/2, the second major version of Hypertext Transfer Protocol (HTTP) and the biggest update in years. HTTP/2 (originally named HTTP/2.0) is the second major version of the HTTP network protocol used by the World Wide Web. It is based on SPDY. It is the first new version of the HTTP protocol since HTTP 1.1, which was standardized back in June 1999.
What is HTTP/2? HTTP/2 is a replacement for how HTTP is expressed “on the wire.” It is not a ground-up rewrite of the protocol; HTTP methods, status codes and semantics are the same, and it should be possible to use the same APIs as HTTP/1.x (possibly with some small additions) to represent the protocol. HTTP/2 is defined for both HTTP URIs and for HTTPS URIs (over TLS, where TLS 1.2 or newer is required). Some implementations, such as Firefox, have stated that they will only support HTTP/2 when it is used over an encrypted connection. It’s very unlikely that you’ll ever see unencrypted HTTP/2. The reason is that there is a lot of existing infrastructure (e.g. proxies, load balancers, firewalls) that would fail if it encountered HTTP/2 frames.
The proposed changes do not require any changes to how existing web applications work, but new applications can take advantage of new features for increased speed. According to A Simple Performance Comparison of HTTPS, SPDY and HTTP/2 article HTTP/2 is likely to provide significant performance advantages compared to raw HTTPS. HTTP/2 reduces the number of connections that have to be setup to download a page.