A free website hosting is a free non-paid web hosting service, usually supports forced ads on subscriber's website for earning revenue. Free web-hosting that does not make use of advertising also exists; these often come with some limits on usage. Free web hosts will usually provide a subdomain (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. Many host provide template builders to make website creation easier. There are also some free domain companies which may provide free third level domain names free with DNS and other facilities.
Some of such popular free web hosts (also called blog hosts) include Blogger and Wordpress. When websites are created with these free website hosting services, the websites get such names as yoursite.blogspot.com and yoursite.wordpress.com.