A subdomain is a website address, which is under a main, or a root domain name. One example is something.domain.com, where domain.com is the main domain, 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 part of the whole web address, a subdomain can be totally independent and also hosted by a separate service provider. Using a subdomain could be very handy if you wish to have different sites which are related in some way. For instance, you could have a web-based store under the main domain and a forum under a subdomain so as to supply means for your customers to ask questions and share thoughts regarding your products. The benefit of employing a subdomain as opposed to a subfolder is that the sites will be separated, so you're able to update one of them or perform maintenance without affecting the other.