A subdomain is a web address, which 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. Each and every subdomain can have its own site and records i.e. aside from using the domain name as a part of the whole web address, a subdomain can be fully independent and even hosted by a different company. Employing a subdomain can be very beneficial if you'd like to have different web sites which are connected in some way. For example, you could have a web-based store under the main domain plus a forum under a subdomain so as to supply means for your clients to ask questions and share thoughts concerning your products. The main advantage of using a subdomain as opposed to a subfolder is that the websites are going to be separated, so that you can update one of them or perform maintenance without affecting the other.