A subdomain is a website url, which is under a main, or a root domain. An illustration is something.domain.com, where domain.com is the main domain, while "something" is the subdomain below it. Every single subdomain can have its own site and records i.e. aside from using the domain name as part of the whole web address, a subdomain can be completely independent and also hosted by a separate service provider. Employing a subdomain can be quite beneficial if you wish to have different sites that are related in some way. For example, you may have an on-line store under the main domain as well as a forum under a subdomain so as to supply means for your customers to ask questions or share opinions about your products. The main advantage of using a subdomain rather than a subfolder is that the websites will be separated, so you can update one of them or perform maintenance without affecting the other.