"WWW" is commonly found at the beginning of web addresses. Many organizations on the Internet follow the convention of naming hosts according to the services they provide. So for example, the host name for a web server is "www"; for an FTP server it's "ftp"; or a news server is "news" or "nntp" (after the news protocol NNTP). The host names are then used as DNS subdomain names, giving the full "www.example.com".
These prefixes are not required by any technical standard; indeed, the first Web server was at "info.cern.ch" [citation needed] and even today many websites are available without the "www" prefix.
Some browsers will automatically try adding "www." to the beginning, and possibly ".com" to the end, of typed URLs if a web page isn't found without them. Internet Explorer and Mozilla Firefox will automatically prefix 'http://www.' and append '.com' to the address bar contents when the Control and Enter keys are pressed simultaneously. For example, entering "example" in the address bar and then pressing Control+Enter causes the browser to visit "http://www.example.com".