A subdomain is a web address, which is under a main, or a root domain. One example is something.domain.com, in which domain.com is the main domain address, while "something" is the subdomain below it. Every subdomain can have its own site and records i.e. aside from employing the domain name as part of the whole web address, a subdomain can be entirely independent and even hosted by a separate company. Employing a subdomain can be extremely practical if you'd like to have different web sites that are related in some way. For instance, you can have a web-based store under the main domain along with a forum under a subdomain so as to supply means for your customers to ask questions or share views about your products. The best thing about employing a subdomain as opposed to a subfolder is that the web sites will be separated, so you are able to update one of them or perform maintenance without affecting the other.