A subdomain is a web address, which is under a main, or a root domain. An illustration is something.domain.com, where domain.com is the main domain address, while "something" is the subdomain below it. Every single subdomain can have its own site and records i.e. apart from employing the domain name as a part of the whole web address, a subdomain can be fully independent and also hosted by a different service provider. Using a subdomain can be very beneficial if you wish to have different websites that are associated in some way. For instance, you may 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 and / or share views concerning your products. The advantage of employing a subdomain as opposed to a subfolder is that the websites are going to be separated, so you are able to update one of them or perform maintenance not affecting the other.