The HTTP protocol structure

HTTP is a network protocol that is used to deliver resources across the World Wide Web (WWW). Resources are usually HyperText Markup Language (HTML) files, but they also include a number of other file types, such as images, audio, and video. Users often enter a URL into a browser to obtain a resource. The term URL stands for Uniform Resource Locator with the emphasis here on resource.

Most people use a browser to communicate across WWW. The browser represents a client application, while the web server responds to client requests. The default port used by these servers is port 80.

HTTP has evolved over the years. HTTP/1.0 originated in the 1980s and 1990s with the first documentation released in 1991. The latest definition of HTTP/1.1 was released as a six-part specification in June 2014. A Request For Comments (RFC) for HTTP 2.0 was released in May 2015. HTTP is an evolving standard.

The following links may prove useful for the interested reader:

Version	Reference...