Country Top-level Domains
In addition to generic top-level domains, another category of domains exists called country code top-level domains, or ccTLDs. These suffixes are two letters long, and are used or restricted to a particular country or territory.
Some ccTLD Internet address suffixes include .us for the United States, .eu for the European Union, .pr for Puerto Rico, .uk for the United Kingdom, and .za for South Africa. In addition, internationalized ccTLDs are currently being implemented that utilize non-Latin characters (for example, for websites bearing simplified Chinese characters) so that further options and localization can be used in choosing a top-level domain.
Depending upon the agency responsible for a specific ccTLD, registration for a country code domain name may require a physical presence in the specific country, or even citizenship. In other instances, registration is open and therefore does not necessarily signify that a particular website has a connection to the country or territory.
Top-level domains have been greatly expanded since they were first introduced. The list of generic top-level domains and country code top-level-domains is already extensive, and grows every year. Luckily, the IANA maintains a list describing the domain, the type of domain, the purpose, and the sponsoring organization of all current top-level domains.