The SPDY protocol was announced by Google in November 2009 and implemented for the first time a year later. SPDY protocol aimed to optimize the old HTTP by implementing compression technologies, multiplexing and encryption. Although it is currently implemented in most browsers, the protocol has not received wide acceptance from sites owners and Google announced that it would replace it with HTTP/2.
Implemented for the first time under the sixth version of the Chrome browser, the SPDY protocol from Google optimized archaic mode of HTTP / 1.1. If this protocol is shared between local browser and the service that it connects, SPDY creates an encrypted tunnel (TLS) that removes HTTP concurrent calls by multiplexing, decreases latencies, compresses declarative fields and optimizes traffic, by prioritizing each network connection. SPDY is currently being implemented under browsers like Chrome, Safari, Firefox, Opera and Internet Explorer, which it provides more coverage than optimal, but owners of online services were less enthusiastic, and in spite of his open, SPDY was implemented late last year by only 2.4% of all existing Websites worldwide.
Google announced that it would implement the Protocol similar to SPDY, and it will be called HTTP / 2 since 40 version of the Chrome browser and it will completely give up SPDY in the first half of 2015. Building on the foundation SPDY 3.x, HTTP / 2 is an upcoming version of the famous Web protocol that will provide the same core features, but will optimize prioritization algorithms, will use TLS extensions for encryption and will enjoy greater acceptance as will be a completely open standard, maintained by the independent Internet Engineering Task Force (IETF). For the average user, the change will be invisible when using services that are already implementing SPDY, but wider adoption of the new protocol HTTP / 2 will allow them to benefit more from these technological advantages. Now, HTTP / 2 is implemented under browsers like Chrome (but not enabled by default in current version 39), Internet Explorer 11 and Mozilla Firefox.