What Is a ccTLD?
Country-code top-level domains
A ccTLD is the two-letter internet domain suffix linked to a country or territory, such as .us for the United States or .jp for Japan. IANA delegates each ccTLD to a registry operator.
ccTLDs are usually derived from the ISO 3166-1 alpha-2 code, but there are exceptions such as the United Kingdom, which uses .uk even though its ISO code is GB.
IANA management
IANA maintains the root zone database that lists every active ccTLD and its sponsoring organization. The root zone file is public and provides a stable reference for the global domain namespace.
When a ccTLD changes operators or policies, the domain itself remains stable for users.
Common examples
Popular examples include .us, .uk, .de, .fr, .jp, .cn, and .au. Country pages in this reference show the ccTLD alongside the ISO codes so the two can be compared.
You can also search a TLD directly, for example .jp, and the lookup resolves to the matching country.