A subdomain is a website url, that is under a main, or a root domain. One example is something.domain.com, where domain.com is the main domain name, while "something" is the subdomain below it. Every single subdomain can have its own website and records i.e. aside from employing the domain name as part of the whole web address, a subdomain can be totally independent and also hosted by a different service provider. Employing a subdomain could be very practical if you want to have different sites that are connected in some way. For example, you could have a web-based 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 views about your products. The main advantage of employing a subdomain instead of a subfolder is that the web sites will be separated, so you can update one of them or perform maintenance without affecting the other.