Domain levels
A domain consists of several parts separated by dots. For example, in the domain "alviy.com": "alviy" is the domain name (or subdomain). "com" is the domain zone (or top-level domain). Together these two parts form a second-level domain. The more dots there are, the more levels there are. The domain "www.alviy.com" is a third-level domain. The Domain Name System (DNS) translates domain names into IP addresses, letting people easily remember the addresses of websites and other Internet resources.
Domain zones
These are top-level domains — TLDs (Top Level Domain). As a rule, the zone points to the type of organization or the region. For example, .com — commercial organizations, .org — non-profit organizations, .net — network services, while .рф and .ru denote the Russian geographic region.