TLD - MDN Web Docs Glossary: Definitions of Web-related terms 编辑

A TLD (top-level domain) is the most generic domain in the Internet's hierarchical DNS (domain name system). A TLD is the final component of a domain name, for example, "org" in developer.mozilla.org.

ICANN (Internet Corporation for Assigned Names and Numbers) designates organizations to manage each TLD. Depending on how strict an administrating organization might be, TLD often serves as a clue to the purpose, ownership, or nationality of a website.

Consider an example Internet address: https://developer.mozilla.org
Here org is the TLD; mozilla.org is the second-level domain name; and developer is a subdomain name. All together, these constitute a fully-qualified domain name; the addition of https:// makes this a complete URL.

IANA today distinguishes the following groups of top-level domains:

country-code top-level domains (ccTLD)

Two-character domains established for countries or territories. Example: .us for United States.

internationalized country code top-level domains (IDN ccTLD)

ccTLDs in non-Latin character sets (e.g., Arabic or Chinese).

generic top-level domains (gTLD)

Top-level domains with three or more characters.

unsponsored top-level domains

Domains that operate directly under policies established by ICANN processes for the global Internet community, for example "com" and "edu".

sponsored top-level domains (sTLD)

These domains are proposed and sponsored by private organizations that decide whether an applicant is eligible to use the TLD, based on community theme concepts.

infrastructure top-level domain

This group consists of one domain, the Address and Routing Parameter Area (ARPA).

Learn more

General knowledge

• TLD on Wikipedia
• List of top-level domains