A subdomain is a website url, that 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 single subdomain can have its own site and records i.e. apart from employing the domain name as part of the whole web address, a subdomain can be fully independent and also hosted by a separate company. Employing a subdomain can be very beneficial if you'd like to have different web sites that are associated in some way. For example, you can have an on-line store under the main domain plus a forum under a subdomain in order to supply means for your customers to ask questions or share opinions regarding your products. The advantage of using a subdomain instead of 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.