The HTTP/2 standard was developed by the Internet Engineering Task Force (IETF) and approved on 14th May 2015. It is based on the SPDY networking protocol developed by Google. HTTP/2 is designed to replace the HTTP/1.1 network protocol used by the World Wide Web and is already supported by most major web browsers. Although the protocol supports both encrypted and unencrypted connections the browser developers took the decision to only support HTTP/2 on encrypted web sites. Therefore a security certificate (SSL) is necessary to enable HTTP/2. Server software for implementation of HTTP/2 requires stronger cipher suites so some older browsers, which lack support for newer encryption algorithms, may be unable to connect.
HTTP/2 network connections are faster than HTTP/1.1 because of the use of data compression for HTTP headers and multiplexed parallel responses with a single connection. In practical terms the benefits of speed improvements to uploads are very important. HTTP/2 Server Push can deliver content that is expected even before the browser requests it. For example when a web page is requested the associated CSS stylesheet can be anticipated and pushed by the server. Multiplexing and prioritising requests reduces the overall download time.