There are three scopes for domains that define the scope we are referring to. The difference needs be clearly understood to avoid confusion.
For a given registered domain example.com we have
- Root Domain scope - i.e. all links referring from/to
- Sub Domain scope - i.e. all links referring from/to
- Page scope, or URL scope - i.e. all links referring from/to a specific page
- TLD referring only to the .com extension.