A country code top-level domain (ccTLD) is an Internet top-level domain generally used or reserved for a country or a dependent territory.
All ccTLD identifiers are two letters long, and all two-letter top-level domains are ccTLDs. Creation and delegation of ccTLDs is performed by the Internet Assigned Numbers Authority (IANA) as described in RFC 1591, corresponding to ISO 3166-1 alpha-2 country codes with few exceptions explained below.