With some marketing material it often shows reference to just a subdomain and top level domain.
In a domain structure the subdomain would come before the domain name then TLD
For a domain example.com.
The subdomain could be visit.example.com
So the structure would be subdomain.domain.tld like the example image.
I just feel that it might cause some confusion if we’re referring to subdomains as domains with some users or new namers