What is a top-level domain (TLD)?

In the DNS hierarchy, a top-level domain (TLD) represents the first stop after the root zone. In simpler terms, a TLD is everything that follows the final dot of a domain name. For example, in the domain name ‘google.com’, ‘.com’ is the TLD. Some other popular TLDs include ‘.org’, ‘.uk’, and ‘.edu’.
TLDs play an important role in the DNS lookup process. For all uncached requests, when a user enters a domain name like ‘google.com’ into their browser window, the DNS resolvers start the search by communicating with the TLD server. In this case, the TLD is ‘.com’, so the resolver will contact the TLD DNS server, which will then provide the resolver with the IP address of Google’s origin server.
The Internet Corporation for Assigned Names and Numbers (ICANN) has authority over all TLDs used on the Internet, and it delegates the responsibility of these TLDs to various organizations. For example, a U.S. company called VeriSign operates all ‘.com’ and ‘.net’ TLDs.
Another purpose of TLDs is to help classify and communicate the purpose of domain names. Every TLD will tell you something about the domain that precedes it; let’s look at some examples:

Examples of TLDs