I have been dreading this first post about HTTP. So I am going to start it off simply by letting Wikipedia articulate what HTTP is, then I will try to put it into my own words.
Hypertext Transfer Protocol (HTTP) is an application-level protocol for distributed, collaborative, hypermedia information systems.
HTTP is a request/response standard between a client and a server. A client is the end-user, the server is the web site. The client making a HTTP request--using a web browser, spider, or other end-user tool--is referred to as the user agent. The responding server--which stores or creates resources such as HTML files and images--is called the origin server.