rotocol) The communications protocol used to connect to Web servers on the Internet or on a local network (intranet). Its primary function is to establish a connection with the server and send HTML pages back to the user's browser. It is also used to download files from the server either to the browser or to any other requesting application that uses HTTP.
Addresses of websites begin with an http://
prefix; however, Web browsers typically default to the HTTP protocol. For example, typing www.yahoo.com
is the same as typing http://www.yahoo.com
. In fact, only yahoo.com
has to be typed in. The browser adds the rest.
HTTPS (HTTP Secure) is the encrypted version of HTTP (see HTTPS
A Stateless Connection
HTTP is a "stateless" request/response system. The connection is maintained between client and server only for the immediate request, and the connection is closed. After the HTTP client establishes a TCP connection with the server and sends it a request command, the server sends back its response and closes the connection.
The first version of HTTP caused considerable overhead. Each time a graphics file on the page was requested, a new protocol connection had to be established between the browser and the server. In HTTP Version 1.1, multiple files could be downloaded with the same connection. It also improved caching and made it easier to create virtual hosts (multiple websites on the same server). See HTTP/2
, HTTP header
Web Server Fundamentals
Web browsers communicate with Web servers via the TCP/IP protocol. The browser sends HTTP requests to the server, which responds by sending back headers (messages) and files (HTML pages, image files, Java applets, etc.). See HTTP header