A subdomain is a web address, that is under a main, or a root domain name. One example is something.domain.com, in which domain.com is the main domain address, while "something" is the subdomain below it. Each and every subdomain can have its own website and records i.e. apart from using the domain name as a part of the whole web address, a subdomain can be totally independent and also hosted by a separate service provider. Using a subdomain can be quite handy if you want to have different web sites which are associated in some way. For example, you may have a web-based store under the main domain and a forum under a subdomain so as to offer means for your clients to ask questions or share views regarding your products. The best thing about employing a subdomain as opposed to a subfolder is that the websites are going to be separated, so you're able to update one of them or perform maintenance not affecting the other.