A free web hosting service is a web hosting service that is free, usually advertisement-supported. Free web hosts will usually provide a sub domain (yoursite.example.com) or a directory (www.example.com/~yourname). In contrast, paid web hosts will usually provide a second-level domain along with the hosting (www.yourname.com). Many free hosts do allow use of separately-purchased domains. 
Rarely, a free host may also operate as a domain name registrar. There are also some free domain companies which may provide free 3rd level domain names free with dns and other facilities.
Usually free webhosts are based on Linux based servers with support to php,mysql and cgi based scripts. The most commonly used control panel for these type of hosting is WHM and vistapanel.
