Domain

The core part of a website's URL (its Internet address). In the URL "www.google.com/ads," the domain name is "google.com."

A domain is usually made up of two parts: a name (like "google") and a category (like ".com") which combine to make a domain name like "google.com." Domains can use industry categories such as .edu and .gov, country categories such as .fr or .jp, or a combination.
There can be many pages or sites within one domain. For example, all of these websites share the domain name "google.com:"
www.google.com
www.google.com/ads
support.google.com/google-ads
Google Ads has several policies that involve the URLs and domain names that you include in your ads. For example, all ads within a particular ad group need to use the same domain in their display URLs.