(Top-Level Domain) The highest-level in the Internet domain naming system. Officially called a "generic top-level domain" (gTLD), it is also known as a "domain suffix" or "domain extension," because the designation is added to the end of the domain name. For example, .com is the gTLD in www.lenovo.com. For details, see Internet domain name.
In the Internet Domain Name System (DNS), the rightmost portion of the address, the TLD identifies the type of entity owning or sponsoring the address, or the country in which the address is located. The several types of Top Level Domains (TLDs) include generic Top Level Domains (gTLDs) and country codes (ccTLDs). The gTLD is always used. If a country code is also used in the address, it becomes the TLD, and the gTLD becomes the secondary domain. See also ccTLD, DNS, domain, gTLD, Internet, and secondary domain.