HTTP is a standard communication protocol for web browsers and servers, that allows them to interact. Hypertext transfer protocol is basically a networking protocol that is used by the software.
The buildup of HTTP is something like this; it is constructed on top of TCP and it is a network protocol used at the application layer. HHTP requests something from the web via HHTP client which are usually browsers and produce responses to the queries.
There are three types of messages in HTTP; GET, POST and HEAD.
Many ports can be used for HTTP, the default is TCP port 80, other options include 8080. HTTPs latest version is the 1.1, which is an upgrade from 1.0 that was prone to certain performance restrictions.