Third-level domains are also known as subdomains. In a URL, the subdomain is written before the domain name. Here are some examples:


Subdomain "affiliates"
http://affiliates.art.com

Subdomain "www"
http://www.rockfound.org

Subdomain "men"
http://men.style.com

Subdomain "mail"
http://mail.google.com

Subdomain "bus"
http://www.bus.umich.edu


These are commonly used for bulk email, email forwarding, and domains for Blackbaud NetCommunity websites.