TLD: definition

A top-level domain, or TLD, is the last part of a domain name, after the final dot. In www.example.com the TLD is .com, and in example.org it is .org. Every domain name on the internet sits under one TLD.

What a top-level domain is

The DNS Domain Name System The internet's directory that links domain names to computer addresses. Full definition of DNS is organized like a tree. At the top is the root zone, and one level below it are the TLDs. The root zone is mainly a list of TLDs and the name server A server that holds a domain's DNS records and answers lookups. Full definition of name server that answer for each of them.

For the DNS itself, a TLD is an ordinary zone. RFC Request for Comments A numbered document in the series recording the internet's technical standards and practices. Full definition of RFC 9499, the technical standard on DNS terms, says there is “nothing special” about TLDs from the point of view of the DNS. The split into country code and generic TLDs is a matter of policy, not technology.

In March 1994, RFC 1591 The 1994 document that still underpins how country code domains are assigned. Full definition of RFC 1591 listed seven generic TLDs (.edu, .com, .net, .org, .gov, .mil and .int) plus the two-letter country codes, and said that other TLDs were “extremely unlikely”. Since June 1999, RFC 2606 has reserved .test, .example, .invalid and .localhost so that they never become real TLDs. Names under .example are meant for documentation.

The main families: generic, country code, sponsored, brand and infrastructure

IANA Internet Assigned Numbers Authority The functions that coordinate the root zone, IP addresses and protocol numbers. Full definition of IANA’s database gives each TLD a type: generic, country-code, sponsored, generic-restricted, infrastructure or test.

Country code (ccTLD). Mainly a two-letter code from the ISO 3166-1 The standard list of country codes that decides which ccTLDs can exist. Full definition of ISO 3166-1 list of country codes, such as .es or .de, plus IDN ccTLD Internationalized Domain Name country code top-level domain A country code TLD written in a non-Latin script. Full definition of IDN ccTLD in non-Latin scripts. IANA follows that list and does not decide what counts as a country. There are a few exceptions, such as .eu (a code exceptionally reserved for the European Union) and .uk (kept although the ISO code for the United Kingdom is GB).
Generic (gTLD). A string becomes a gTLD after it passes ICANN Internet Corporation for Assigned Names and Numbers The nonprofit that coordinates the global DNS and gTLD policy. Full definition of ICANN’s evaluation and signs a contract with ICANN, as .com, .org and .app did. Place names such as .madrid and .barcelona are also generic, run by the Comunidad de Madrid and the Municipi de Barcelona. Country and territory names are not approved as gTLDs.
Sponsored (sTLD Sponsored Top-Level Domain A gTLD run with a sponsor for a specific community. Full definition of sTLD). As of October 2026, IANA lists 14, including .aero, .cat, .edu, .gov, .int and .museum.
Brand (.brand A top-level domain that a company runs for its own trademark. Full definition of .brand). Not an IANA type: .bmw, for example, appears as generic. “.Brand” is a status in the ICANN contract. The string must match a registered trademark the operator owns and uses, and only the operator, its affiliates or its trademark licensees may hold names.
Infrastructure. Only .arpa An infrastructure-only top-level domain, best known for holding reverse DNS records. Full definition of .arpa, used for technical needs such as in-addr.arpa and ip6.arpa, which map numeric internet addresses back to names. IANA runs it under the guidance of the Internet Architecture Board (IAB).

Open versus restricted TLDs

In an open TLD, anyone can register a name. In a restricted TLD A TLD that only eligible people or organizations can register domains in. Full definition of restricted TLD, only people or organizations that meet set rules can register. Those rules can come from three places, and in each case the registry enforces them:

Registry policy. A gTLD registry may set non-discriminatory criteria that are reasonably related to how the TLD works.
The ICANN contract. A community TLD A gTLD run for a defined community, with registration limits. Full definition of community TLD must have registration Obtaining the right to use a domain name for a set period. Full definition of registration policies that cover, at a minimum, who may register and which names they may choose.
Law. Regulation (EU) 2019/517 opens .eu to EU citizens, EU residents and organizations established in the EU. The registry may revoke a name whose holder does not meet these criteria.

A ccTLD can also be open in practice. Since 2005, Spain’s national plan allows any person or entity with interests in or ties to Spain to register under .es, and these ideas are read broadly.

A generic word cannot be closed to a single owner, and as of October 2026 ICANN will not approve “closed generic A TLD based on a common word that only its own registry may use. Full definition of closed generic” applications until it has an approved way to judge whether they serve the public interest. A .brand is closed by design, because its string is a trademark, not a generic word.

Who runs a TLD and who sets its rules

Every delegated TLD has a manager listed by IANA. In industry terms, this organization runs the registry and decides, within its rules, who may register names and on what terms. Requests to add or change a TLD in the root zone go through IANA.

The rules differ by family:

gTLDs. The registry signs a Registry Agreement The contract between ICANN and a gTLD registry operator. Full definition of Registry Agreement with ICANN. It must follow consensus policy An ICANN community rule that gTLD registries and registrars must follow. Full definition of consensus policy, developed mainly in the GNSO Generic Names Supporting Organization The ICANN body that develops policy for generic top-level domains. Full definition of GNSO, and in most cases sell names only through ICANN-accredited registrar A company that registers domain names for customers with the registry. Full definition of registrar.
ccTLDs. ICANN’s Bylaws limit its policy role on second-level registrations to gTLDs. The ccNSO Country Code Names Supporting Organization The ICANN body where ccTLD managers develop global ccTLD policy. Full definition of ccNSO develops global policies for ccTLDs, but few of them bind its members, so most rules are local. For example, .es is managed by Red.es The Spanish public body that manages the .es domain through its unit Dominios.es. Full definition of Red.es under a Spanish ministerial order. When a ccTLD is delegated or transferred, the government concerned is consulted for support or non-objection.

How to choose a TLD for a project

There is no single right answer, but some questions can be checked:

Eligibility. Can the registrant The person or organization that holds a domain name registration. Full definition of registrant register in the TLD at all, and are the rules set by ICANN policies or by local law? A company with ties to Spain but no establishment in the EU may meet the .es rule but not the .eu criteria. Brand and community TLDs are not open to everyone.
Audience. A country code stands for a country or territory.

Rules change, so check the registry’s current policy, and ask a lawyer when the answer depends on a specific situation.

How many TLDs exist and how new ones are added

As of October 2026, IANA’s Root Zone Database lists about 1,400 TLDs with a manager. This counts database entries, not the live root zone.

A new ccTLD usually follows a new code in the ISO 3166-1 list, through a delegation request with government consultation.

new gTLD A generic top-level domain added to the internet through ICANN's New gTLD Program. Full definition of new gTLD come through ICANN application rounds. As of October 2026, in the 2026 Round ICANN's second round of applications for new generic top-level domains. Full definition of 2026 Round:

Applications were accepted from 30 April to 12 August 2026, with an evaluation fee of USD 227,000 per application for most applicant An organization that has applied to ICANN to run a new gTLD. Full definition of applicant.
ICANN’s snapshot of 7 October 2026 showed 1,615 applications, including 333 brand, 16 community-based and 15 self-identified geographic applications.
String Confirmation Day is 17 November 2026, and the community input and objections period runs from that day to 16 March 2027. A prioritization draw follows in 2027.

A TLD that passes evaluation and contracting The stage when a successful applicant signs its Registry Agreement with ICANN. Full definition of contracting is then delegated: it is added to the root zone and starts to work.

TLD