A subdomain, as the name suggests, is a division of the main domain. It is mostly created in cases where you wish to cover content which is completely different from that included in the rest of the site. A subdomain is a separate site in itself. However, all the subdomains are linked to the main site. Subdomain name comes on the left of the domain name. For example, blog.healthandfitness.com and garments.healthandfitness.com are subdomains of the website, www.healthandfitness.com.