What are second-level and third-level domain names?

A second-level domain is the part of a domain name or website address that comes before the top-level domain (tld).

Ex: In janesmith.realtor, “janesmith” is the second-level domain and .realtor™ is the tld.

A third-level domain name is the part of a domain name or website address that comes before the second-level domain name. Third-level domains are also called “sub-domains” as they sometimes refer to specific sections or pages of a website.

Ex: In offices.janesmith.realtor, “offices” is the third-level domain, “janesmith” is the second-level domain, and .realtor™ is the tld.