A subdomain is a website address, that's under a main, or a root domain. An illustration is something.domain.com, where domain.com is the main domain name, while "something" is the subdomain below it. Each and 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 completely independent and even hosted by a different provider. Using a subdomain can be extremely beneficial if you'd like to have different web sites which are associated 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 offer means for your customers to ask questions and / or share thoughts about your products. The benefit of employing a subdomain instead of a subfolder is that the websites are going to be separated, so you're able to update one of them or perform maintenance without affecting the other.