Top-level domains (TLDs) are what make up the highest level of the domain name system (DNS), the internet’s directory service. Making up the final part of an internet address, they’re often referred to as domain endings. The function of these endings is to help simplify the classification process of all registered addresses in the DNS. To this end, ICANN (Internet Corporation for Assigned Names and Numbers) assigns country-specific top-level domains, or ccTLDs (country code TLDs), which are then managed by their respective countries. Domain guidelines define conditions that apply to the ccTLD’s registration (e.g. which characters are allowed, minimum/maximum length, or location). Additionally, ICANN also conveys theme-specific TLDs (gTLDs), like .com, a domain once exclusively reserved for American companies–to domain registries.
Country domain names
ccTLDs are always made up of a two-letter code that is assigned to every country according to the 1974 ISO-3166 standard. In addition to these countries, oversea territories separated from their mainland counterparts also receive their own ccTLDs based on the same ISO standard. Following this, in addition to the Australian domain, .au, there are also distinct ccTLDs for the country’s distant territories of the Coco Islands (.cc), the Christmas Islands (.cx), Norfolk Island (.nf), or the Heard and McDonald Islands (.hm). There are also two exceptions that deviate from the standard coding. These are:
- The United Kingdom uses the ccTLD .uk, although the ISO domain .gb, while registered, isn’t used
- Although it’s not a sovereign state (or a dependent territory), the European Union uses the ccTLD, .eu, thanks to an exemption from the standard protocol.
The fact that every country has the right to determine its own guidelines for assigning its domain leads to considerable variation. In France, for example, anyone wishing to register their domain under .fr first needs to have their residency or company headquarters located within France. And until 2009, Germany required all .de TLDs to be composed of at least three characters, of which at least one had to be a letter. Many smaller or poorer countries have capitalized on these domain assignment rules by strategically marketing their ccTLDs:
- .to: the ccTLD of the island nation of Tonga has been managed by the domain registry, Tonic, since 1997. The assignment process takes places automatically, regardless of the applicant’s actual residency. And the fact that Tonic doesn’t carry out a whois search means that .to domain owners remain completely anonymous, making it a very popular domain for file sharing as well as other controversial video services.
- .tv: the microstate of Tuvala was able to cash in on $50,000,000 when it sold its ccTLD to the company DotTV, which then marketed its purchase as a television domain. The money went to financing IT infrastructure as well as paying the admission fee for the UN.
- .ag: the top-level domain, .ag, is actually for the independent state of Antigua and Barbuda. It’s also often used by many large German businesses whose legal entities are organized as Aktiongesellschaften, or joint-stock companies.
- .me: Montenegro’s country top-level domain has experienced a massive flood of registrations since first becoming available in 2008. .me domains, which often take on constructs like love.me, are often auctioned off upon registration. A notable example was seen in 2011 when the domain meet.me was sold for $450,000.
In addition to the over 200 ccTLDs, there’s also a host of internationalized TLDs, which contain umlauts, diacritic characters, or letters from non-Latin alphabets. These IDN top-level domains have been around since 2010 and allow virtually all Unicode characters, although individual registries are still able to determine which characters are allowed. A complete list of top-level domains for countries as well as a collection of internationalized TLDs can be found on Wikipedia.
Changes in the ccTLD system
Given the geographical and political background of country code top-level domains, it’s often the case that some changes need to be made. Even today, ICANN is often busy with the task of both deleting no-longer relevant ccTLDs as well as registering new ones. Proof of just how long some of these cases can drag out can be seen in some of the ongoing cases involving country ccTLDs of the former Soviet Union. Although the USSR collapsed in 1991, it remains possible even to this day to register a domain under .su. The following domains have been successfully deleted and thus count as former ccTLDs:
- .an: citizens of the Netherlands Antilles were able to register with an .an address until the country was dissolved in 2010. ICANN accepted the domains .bq (Caribbean Netherlands), .cw (Curaçao), and .sx (Sint Maarten), which have since fully replaced .an
- .dd: the .dd domain was originally intended for the GDR (German Democratic Republic), which still existed when the ccTLDs were first introduced. The domain only ever served an internal use between two East German universities.
- .um: this top-level domain was dissolved in 2008 and refers to the United States Minor Outlying islands, a group of uninhabited pacificislands managed by the University of Southern California. After it became defunct, the ICANN removed the domain in response to the University’s wish to no longer bare responsibility for the domain.
- .yu: the former Yugoslav Republic’s ccTLD and its since dissolved predecessor state, Serbia and Montenegro, was removed in 2010 after .yu website owners were able to divide the domain into .rs (Serbia) and .me (Montenegro).
- .zr: shortly after the country code top-level-domain for the Republic of Zaire was introduced, the African state changed its name to the Democratic Republic of Congo in 1997 and was assigned its new domain, .cd, at the same time. The domain ending .zr was finally deleted by ICANN in 2001.
Top-level domains worldwide
The new top-level domains (nTLDs) can be listed in global comparison. In 2015, over 160 million domains were registered, but regarding ccTLDs it was a little bit less with 150 million.
The most popular domain ending is still the top-level domain .com, the second is the country domain, .cn for the People’s Republic of China.
Click here to download the infographic about top-level domains.