A type of protocol that aids the transmission of data across the Internet. HTTP is a relatively simple protocol that allows the sending of a request, optionally with some data attached, to a computer, or ‘server’, and the subsequent reply with information about the request, usually with some data attached, as specified in the request. The send and reply include the identities of the sender and receiver of the request, together with other information, such as the size of the attached data. Usually the data attached to the reply is an HTML file (see hypertext markup language) or media object, such as an image or video clip. Data attached to the request can be common gateway interface (CGI) data to specify extra information for a database or other programs running on the server.