An interesting topic of discussion surrounds the thought of whether a sub-domain should have the www prefix attached to it. The idea to deploy a site using sub-domains vs sub folders is an entirely different topic, but if you do make use of sub-domains, you’ll want to read further. For those unaware, subdomains are simply a domain that is part of a larger domain. For example, ask.enquiro is a sub-domain of www.enquiro.com. Although it is part of the main Enquiro domain, sub-domains such as ask.enquiiro are treated as separate entities by search engines.