Domain name is unique. This is both intentional and essential to enable each site to be correctly and easily accessed and referenced from any other computer on the internet. The downside is that in the third decade of the web it can be difficult to find a suitable name that is still available.
When asked to specify a web address, most people will start with ‘www’ without realizing that part is typically not necessary. The characters preceding the first dot in the URL aren’t included in the actual domain name.
During the web’s infancy, the www referred to the ‘World Wide Web’ portion of the domain. In other words, when someone sought to visit www.company.com, the ‘www’ indicated the viewer should be shown the content housed on the web portion of the Internet.
As the web grew up, and pretty much took over the internet, companies started using the portion in front of the domain to differentiate between departments, services, or products. This means the domain preface (AKA sub domain) is like a shortcut telling the system which portion of the company’s content to display. So, in the case of Google and its many services, the official domain name is google.com but if you’re looking for Google Docs, the address is docs.google.com. Maps? That’s maps.google.com. Email? You get where we’re going with this: mail.google.com.
To choose a domain name, you need only focus on two things: the name itself and the extension. Your full domain name (not including the preface) must be no more than 67 characters in length.