A subdomain is a website address, that's under a main, or a root domain. One example is something.domain.com, in which domain.com is the main domain, while "something" is the subdomain below it. Every single 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 fully independent and also hosted by a separate provider. Employing a subdomain can be quite beneficial if you wish to have different web sites that are related in some way. As an example, you could have an on-line store under the main domain plus a forum under a subdomain so as to provide means for your clients to ask questions and share thoughts regarding your products. The benefit of using a subdomain as opposed to a subfolder is that the web sites will be separated, so you're able to update one of them or perform maintenance not affecting the other.