Domain extensions: what they are and every type of TLD

What is a domain extension?

blogsubdomain.examplesecond-level domain.comtop-level domain

Domain names are a tree of labels read from right to left. In blog.example.com, .com is the top-level domain, "example" is the name someone registered under it, and "blog" is a subdomain its owner created. Domain ending, domain suffix and website extension all mean the same thing as top-level domain; the TLD glossary entry has the formal definition.

The extension is the part you choose but don't own. When you register example.com, you hold the name "example" inside the .com namespace, through a registrar, for as long as you keep renewing it. The registry's rules come with the name: who may register, what it costs, how disputes are settled. Some countries add a layer of their own, which is why names like example.co.uk exist; see second-level domains and the root zone.

The root zone at a glance

These are the domain extensions in the root zone today. "Active" means delegated: the TLD is in IANA's root zone and its name servers answer queries. The figures update with every data refresh; How many TLDs are there? has the year-by-year breakdown.

Types of domain extensions

There are two main types of domain extensions: generic TLDs (gTLDs) like .com and .app, and country-code TLDs (ccTLDs) like .de and .jp. A small group of special-use names, such as .test and .onion, is reserved for technical purposes. Brand TLDs and non-Latin TLDs cut across these groups.

Generic extensions (gTLDs)

Generic TLDs aren't tied to a country. The first ones date from the 1980s; RFC 1591 (1994) describes .com for commercial use, .net for network providers and .org for other organizations, and by 2011 there were 22 generic endings. ICANN's New gTLD Program opened for applications on 12 January 2012 and received 1,930 of them. 1,105 of today's 1,127 generic TLDs came out of that program. Most are open to anyone; some, like .bank, check who registers, and community endings such as .aero are listed by IANA simply as generic. See gTLD and sponsored TLD.

Country-code extensions (ccTLDs)

Country-code TLDs are two letters taken from the ISO 3166-1 list: .de for Germany, .jp for Japan, .co for Colombia. Under RFC 1591, IANA delegates them to a manager for each country but doesn't decide what counts as a country. There are 248 two-letter codes and 61 in local scripts. A few break the ISO pattern, like .uk and .eu, and some became famous for what they spell, like .io, .tv and .ai. That is how domain hacks began. Each country sets its own rules; see ccTLD.

Brand extensions (dotBrand)

366 active TLDs are brand TLDs under Specification 13 of ICANN's registry agreement. A company like Google or BMW runs the ending for itself, and nobody else can register a name in it. IANA counts them as generic. See the brand TLD list and what a brand TLD is.

Non-Latin extensions (IDNs)

151 extensions are written in other scripts, such as Cyrillic, Arabic, Chinese or Korean, and stored in the DNS as "xn--" codes (Punycode). The first three, Arabic-script country codes for Egypt, Saudi Arabia and the United Arab Emirates, entered the root zone on 5 May 2010. See every IDN TLD and how Punycode works.

Special-use and reserved names

Some names are reserved by IETF standards so software treats them specially and nobody can register them: .test, .example, .invalid and .localhost (RFC 6761), .local for multicast DNS and .onion for Tor. .arpa is different: it is in the root zone and resolves like any TLD, but it is reserved for internet infrastructure and managed by the Internet Architecture Board. See the special-use list.

Retired and unusual endings

153 TLDs have left the root zone, from codes of countries that no longer exist, like .yu and .zr, to brand TLDs their owners handed back: that is the TLD graveyard. Others are odd but very much alive, like .pizza, .horse and .wtf; see weird domain extensions.

Common extensions and what they mean

The oldest domain extensions and their meanings were written down in RFC 1591 in 1994. Today .com, .net and .org are open to anyone, whatever the original purpose; .edu, .gov, .mil and .int still restrict who can register. The current rules are on each extension's page.

Where today's extensions came from

1. 1984 RFC 920 sets out the first generic names (.gov, .edu, .com, .mil, .org) and the use of two-letter country codes.
2. 1985 The first generic TLDs, including .com, .net and .org, enter service.
3. 1994 RFC 1591 describes how TLDs are structured and how ccTLD managers are delegated.
4. 1998 ICANN is set up to coordinate the domain name system.
5. 2000–2004 Two small rounds add endings such as .info, .biz, .aero, .asia and .mobi.
6. 2010 The first country codes in non-Latin scripts go live.
7. 2012 ICANN's New gTLD Program receives 1,930 applications; delegations begin in October 2013.
8. 2014 The busiest year on record, with 397 of today's TLDs delegated.

Growth since then has come almost entirely from that 2012 round: new gTLDs went from zero to more than a thousand in a few years, while the number of country codes barely moved. ICANN has been preparing another application round; its New gTLD Program site has the current timetable. Browse the oldest and newest TLDs, or test yourself with Older or Newer?.

Who runs the system: ICANN, IANA, registries and registrars

ICANN

Sets policy for generic TLDs, signs registry agreements, accredits registrars and runs the application rounds for new gTLDs.

IANA

Run by PTI, an ICANN affiliate. Maintains the root zone database: which TLDs exist, who manages each one and which name servers answer for it.

Registry operator

Runs a TLD's database and name servers and sets its rules within its contract or national policy: VeriSign Global Registry Services for .com, Nominet UK for .uk, EURid vzw for .eu.

Registrar

Sells names to the public and passes each registration to the registry. Registrars for generic TLDs are accredited by ICANN.

94% of delegated TLDs are DNSSEC-signed, which lets resolvers check that answers haven't been forged; here are the ones that aren't. More in registry vs registrar and DNSSEC.

Browse country codes by region

Country codes are easiest to explore by region. Each regional page lists every ccTLD with its flag, its manager and whether it is DNSSEC-signed. The 3D map puts them on a globe, and Globe Hunt and Guess the Country test what you remember.

Browse extensions by industry

Hundreds of newer extensions target a trade or an interest, such as .studio, .law, .shop or .bank. We group them into topic lists. The tags are our editorial judgment, not an official category, so a TLD can appear in more than one.

Curated lists worth a look

Compare popular endings side by side

Each comparison puts two endings next to each other: what they are, how old they are, who runs them, how search engines treat them and when each one makes sense. They don't rank by price. Start with .io vs .com or browse every comparison.

Picking one: where to go next

Choosing an extension for a new site? Start with the decision guide, How to choose a domain extension: a 5-step framework, which goes through audience, eligibility, trust and practical checks in that order. For a name that reads as one word, like stud.io, try the domain hack finder. For a single country, start with that country's page under country codes.

Learn the extensions by playing

The fastest way to remember which country owns .tv or .nu is to guess. Try the Daily Challenge, the Flag Quiz, Real or Fake? or Speed Run; every right answer earns XP, and every TLD page you open stamps your passport. All games are on the Play page.

Ready to register one?

tldplay is made by the team behind Atak Domain, Domain Name API and Whois.com.tr, and every link to them is labeled. The facts on this page come from IANA and ICANN, not from what any registrar sells.