A subdomain is a website address, which is under a main, or a root domain name. An illustration 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 website and records i.e. aside from employing the domain name as part of the whole web address, a subdomain can be totally independent and even hosted by a separate service provider. Employing a subdomain can be very practical if you'd like to have different sites that are connected in some way. For example, you may have an online store under the main domain and a forum under a subdomain in order to offer means for your customers to ask questions and / or share opinions concerning your products. The benefit of using a subdomain rather than a subfolder is that the websites will be separated, so you are able to update one of them or perform maintenance without affecting the other.