HTTP

Hypertext Transfer Protocol is the basis of data communication for the Internet and defines the standards in exchange of hypertext. It is developed to enable intermediate network components to communicate on behalf of servers and clients. HTTP is the application layer protocol within the IP suite.

This is just basically a series of network request-response sessions by a server and client which uses port 80. (A client contact a server/host through an HTTP request, then a server gives a response to the client with status details on the request.)