Top-level domain (TLD) refers to the last segment of a domain name, or the part that follows immediately after the “dot” symbol. TLDs are mainly classified into two categories: generic TLDs and country-specific TLDs. Examples of some of the popular TLDs include .com, .org, .net, .gov, .biz and .edu. The Internet Corporation for Assigned Names and Numbers (ICANN), is the entity that coordinates domains and IP addresses for the internet.
Historically, TLDs represented the purpose and type of domain. ICANN has generally been very strict about opening up new TLDs, but in 2010, it decided to allow the creation of numerous new generic TLDs as well as TLDs for company-specific trademarks.
Top-level domains are also known as domain suffixes.