A subdomain is a domain that is located inside another domain (for example: sales.yourdomain.com is a subdomain of yourdomain.com). Subdomains are very powerful tool to create `subsites` under your main site.

Typical examples of a subdomain are for additional functionality (eg: creating a forums.yourdomain.com for your forums) or for locale-specific versions of your website (for example: a `uk` subdomain for your UK branch and a `fr` subdomain for your French branch).

Unlike other hosting companies, FastVision does not charge you extra for additional subdomains - every single domain has unlimited subdomains.