LearnPart 3 of 8
Domain extensions: gTLD, ccTLD and two-level extensions
The extension is the part after the name, like .com, .de or .co.uk. Generic extensions (gTLDs) are open worldwide, country code extensions (ccTLDs) belong to a country, and some countries split theirs into categories, which is where two-level extensions like .co.uk come from. The list of domain extensions has every one in the root zone.
In 30 seconds
- The extension is the ending of a domain: .com, .de, .co.uk.
- Generic ones (gTLDs) like .com are open to anyone in the world.
- Country code ones (ccTLDs) like .de belong to a country, which sets the rules.
- Some countries add a category level, which is why .co.uk and .com.au exist alongside .uk and .au.
Words with a dotted underline explain themselves: tap or hover them.
What an extension is
The extension is everything to the right of the name you register. Its last label is the top-level domain (), which sits directly under the root of the DNS tree. Each TLD is run by one organisation, its , which keeps the master list of names registered in it and decides its rules.
The full list of TLDs lives in the root zone, maintained by IANA. Over 1,400 extensions are in it today, and every one of them is a separate database with its own registry, rules and registrars. Who does what.
The kinds of extension
| Kind | Examples | What it means |
|---|---|---|
| Generic (gTLD) | .com .net .org .info | Open to anyone in the world. The original handful date from the 1980s. |
| New generic | .app .shop .xyz .online | Launched since 2013 under ICANN's New gTLD Program. Over a thousand of them, many built around a word or topic. |
| Generic, restricted | .biz .name .pro | Generic, with rules about who or what they are for. |
| Sponsored (sTLD) | .edu .gov .aero .museum .travel | Run for a specific community, which sets who may register. |
| Country code (ccTLD) | .uk .de .jp .ca .au | Two letters for a country or territory, run under that country's rules. |
| Internationalised (IDN) | .рф .中国 .한국 | Extensions in other scripts, both country codes and generic ones. |
| Brand | .google .bmw .apple | Owned by one company for its own use. Nobody else can register under them. |
| Infrastructure | .arpa | Used by the internet itself, for example to turn IP addresses back into names. |
gTLD vs ccTLD
| Generic (gTLD) | Country code (ccTLD) | |
|---|---|---|
| Example | .com, .org, .app | .uk, .de, .jp |
| Rules set by | ICANN's policies, applied by each registry | The country's registry and law |
| Who can register | Anyone, for almost all of them | Anyone for many; some need a local address or business |
| Signals | International or no particular place | A connection to that country |
| Disputes | ICANN's dispute policy (UDRP) | Each country's own process |
| Public records | Through RDAP at the registry and registrar | Varies by registry |
Country codes used worldwide
Some country codes spell something useful in English, so they are used far beyond their country. .io is the British Indian Ocean Territory and became the default for developer tools; .ai is Anguilla and became the home of AI products; .co is Colombia, .me is Montenegro, .tv is Tuvalu and .fm is Micronesia.
These work like any other extension, and search engines treat the widely used ones as generic. The country's registry still sets their rules, so read them before you rely on one for a brand.
One-level and two-level extensions
A one-level extension is a single label: example.com, example.de, example.uk. A two-level extension adds a category between the country code and your name: example.co.uk, example.com.au, example.co.jp. You register the whole thing, example.co.uk, exactly as you would register example.com.
Many countries started with categories only (co for companies, org for organisations, ac for universities) and later opened direct registrations too. That is why a UK business can have both example.co.uk and example.uk, and why they can belong to different people.
| Country | Direct | Common two-level | Who can register |
|---|---|---|---|
| United Kingdom | .uk | .co.uk, .org.uk, .me.uk, .ltd.uk, .ac.uk, .gov.uk | Anyone; .ltd.uk is for registered companies and .ac.uk and .gov.uk are restricted |
| Australia | .au | .com.au, .net.au, .org.au, .id.au, .edu.au, .gov.au | An Australian presence; .com.au needs an Australian business |
| New Zealand | .nz | .co.nz, .org.nz, .net.nz, .ac.nz, .govt.nz | Anyone; some categories are restricted |
| Japan | .jp | .co.jp, .ne.jp, .or.jp, .ac.jp, .go.jp | A Japanese address; .co.jp is one per company registered in Japan |
| Brazil | .com.br, .net.br, .org.br | A Brazilian person or company | |
| South Africa | .co.za, .org.za, .net.za | Anyone for .co.za | |
| India | .in | .co.in, .net.in, .org.in, .firm.in | Anyone |
Owning example.co.uk gives you nothing under example.uk or example.com. Each extension is a separate registration. If the name matters, register the versions you need.
The public suffix list
A browser can't tell from the name alone that co.uk is an extension while example.co.uk is someone's domain. It needs to know, so a site can't set a cookie for all of .co.uk, and so the address bar can highlight the part that matters.
The answer is the public suffix list, a shared, volunteer-maintained list of every extension under which people can register names. It also lists platform addresses such as github.io, so that yourname.github.io and someone-else.github.io are kept apart like separate domains. Browsers, email services and certificate authorities all use it.
Names that are never sold
A few names are set aside so they never clash with real domains. Use them in documentation, tests and private networks.
| Name | Use |
|---|---|
| example.com, example.org, example.net, .example | Documentation and examples, like the ones on this page. |
| .test | Testing. |
| .invalid | Names that are meant never to work. |
| .localhost | Your own machine. |
| .local | Devices finding each other on a home or office network. |
| .internal | Private networks inside a company. |
Explore popular extensions
Filter the most-used extensions by kind, or search by name, registry or what they are used for. Each links to its page in the list of domain extensions.
| Extension | Type and registry | What it is |
|---|---|---|
| .com | Generic (gTLD)Verisign | The default commercial TLD and still the most trusted extension on the internet. |
| .net | Generic (gTLD)Verisign | Originally for network infrastructure, now a common .com fallback. |
| .org | Generic (gTLD)Public Interest Registry | Associated with non-profits and organisations, open to anyone. |
| .io | Country code (ccTLD)Internet Computer Bureau | The startup darling. Technically the ccTLD for the British Indian Ocean Territory, used worldwide for tech. |
| .ai | Country code (ccTLD)Government of Anguilla | The ccTLD for Anguilla, now the default extension for AI products. Often sold on a two-year minimum. |
| .co | Country code (ccTLD)GoDaddy Registry | Colombia's ccTLD, marketed globally as a short, brandable .com alternative. |
| .app | Generic (gTLD)Google Registry | Google-run, secure by default. Every .app site must be served over HTTPS.Rules: HTTPS required (HSTS preloaded) |
| .dev | Generic (gTLD)Google Registry | Google-run developer TLD, HTTPS enforced. Popular for portfolios and docs.Rules: HTTPS required (HSTS preloaded) |
| .xyz | Generic (gTLD)XYZ Registry | Cheap, generic, and widely adopted. Watch the gap between first-year and renewal pricing. |
| .me | Country code (ccTLD)Domen | Montenegro's ccTLD, marketed for personal sites and 'about me' pages. |
| .info | Generic (gTLD)Identity Digital | Informational sites. Cheap to start, with a steeper renewal. |
| .biz | Generic, restrictedGoDaddy Registry | Business-focused alternative to .com, in use since 2001.Rules: Business or commercial use |
| .online | Generic (gTLD)Radix | Broad, generic TLD. The first-year discount is steep, the renewal is not. |
| .store | Generic (gTLD)Radix | Retail-focused TLD. Renewal pricing is on the higher end, so budget for it. |
| .tech | Generic (gTLD)Radix | Explicitly technical TLD with a meaningful renewal cost. |
| .site | Generic (gTLD)Radix | Generic and flexible. Common first-year promo, higher renewal. |
| .shop | Generic (gTLD)GMO Registry | Clear commerce signal. Popular for storefronts and brands. |
| .cloud | Generic (gTLD)Aruba | Cloud and infrastructure branding, reasonable renewal. |
| .co.uk | Country code (ccTLD), two-levelNominet | The default for UK businesses. Cheap to renew and free to transfer.Rules: UK presence recommended |
| .uk | Country code (ccTLD)Nominet | Shorter UK extension introduced alongside .co.uk.Rules: UK presence recommended |
| .de | Country code (ccTLD)DENIC | Germany's ccTLD and one of the largest in the world by registrations.Rules: German admin contact required |
| .ca | Country code (ccTLD)CIRA | Canada's ccTLD with a Canadian-presence requirement.Rules: Canadian presence required |
| .eu | Country code (ccTLD)EURid | Pan-European TLD, restricted to EU/EEA residents and organisations.Rules: EU/EEA residency required |
| .us | Country code (ccTLD)GoDaddy Registry | United States ccTLD, requires a US connection.Rules: US nexus required |
| .au | Country code (ccTLD)auDA | Australia's short-form ccTLD. Requires an Australian presence.Rules: Australian presence required |
| .com.au | Country code (ccTLD), two-levelauDA | The commercial Australian extension, tied to a registered business number.Rules: Australian ABN/ACN required |
| .co.nz | Country code (ccTLD), two-levelInternetNZ | New Zealand's commercial extension. |
| .in | Country code (ccTLD)NIXI | India's ccTLD, open to anyone. |
| .fr | Country code (ccTLD)AFNIC | France's ccTLD, requires an EU presence.Rules: EU presence required |
| .es | Country code (ccTLD)Red.es | Spain's ccTLD. |
| .it | Country code (ccTLD)Registro.it | Italy's ccTLD, requires an EU presence.Rules: EU presence required |
| .nl | Country code (ccTLD)SIDN | The Netherlands' ccTLD, one of Europe's most popular. |
| .tv | Country code (ccTLD)Verisign | Tuvalu's ccTLD, universally used for video and streaming. |
| .cc | Country code (ccTLD)Verisign | Cocos Islands ccTLD, used as a generic global alternative. |
| .gg | Country code (ccTLD)Island Networks | Guernsey's ccTLD, adopted heavily by gaming and esports. |
| .so | Country code (ccTLD)GoDaddy Registry | Somalia's ccTLD, used for short brandable names. |
| .sh | Country code (ccTLD)ICB | St Helena's ccTLD, beloved by developers for shell-script puns. |
| .design | Generic (gTLD)Top Level Design | Clear creative signal for studios and designers. |
| .studio | Generic (gTLD)Identity Digital | Popular with creative studios and makers. |
| .art | Generic (gTLD)UK Creative Ideas | For artists, galleries, and the creative world. |
| .blog | Generic (gTLD)Knock Knock WHOIS There | Run by Automattic. A clear signal for writing and publishing. |
| .page | Generic (gTLD)Google Registry | Google-run, HTTPS enforced. Good for simple landing pages.Rules: HTTPS required (HSTS preloaded) |
| .live | Generic (gTLD)Identity Digital | Events, streaming, and anything happening now. |
| .club | Generic (gTLD)GoDaddy Registry | Communities, memberships, and clubs of every kind. |
| .life | Generic (gTLD)Identity Digital | Broad lifestyle TLD, often promo-priced in year one. |
| .world | Generic (gTLD)Identity Digital | Generic and expansive, good for global brands. |
| .co.za | Country code (ccTLD), two-levelZADNA | South Africa's commercial extension. |
| .pro | Generic, restrictedIdentity Digital | Aimed at professionals and licensed practitioners. |
| .vip | Generic (gTLD)GoDaddy Registry | Premium and membership branding. |
| .tools | Generic (gTLD)Identity Digital | Literal and useful for utility and software products. |
| .agency | Generic (gTLD)Identity Digital | Clear positioning for agencies and studios. |
Choosing an extension
- .com is still what most people type by default. If you can get it, it is a safe choice anywhere in the world.
- A country code tells local customers you are local, and is often easier to get a short name in. Check who can register.
- A new generic extension can say what you do in the name itself, like .shop or .studio. Check the renewal terms, not just the first year.
- Some extensions, like .app and .dev, only work over HTTPS. That is a feature, but your host must support it.
- Search many extensions at once with the bulk domain search.
Questions people ask
What is the difference between a gTLD and a ccTLD?
A gTLD (generic top-level domain) like .com or .app isn't tied to a place and follows ICANN's global rules. A ccTLD (country code top-level domain) like .de or .jp is a two-letter code for a country or territory, and that country's registry sets its rules, which sometimes include living or trading there.
Is .co.uk a top-level domain?
No. The top-level domain is .uk. .co.uk is a second-level extension under it, set aside for commercial use, so example.co.uk is a domain registered under the .co.uk extension.
How many domain extensions are there?
Over 1,400 top-level domains are in the root of the DNS: about 250 two-letter country codes, their versions in other scripts, and well over a thousand generic extensions, most of them launched since 2013.
Does the extension affect search rankings?
Generic extensions, old or new, are treated alike. Country code extensions tell search engines the site is aimed at that country, except for the codes that are widely used worldwide, such as .io, .ai, .co, .me and .tv, which search engines treat as generic.
Can anyone register a country code domain?
It depends on the country. Many, like .io, .co, .me, .nz and .uk, are open to anyone. Others, such as .ca, .com.au and .jp, ask for a local presence, a registered business, or an address in the country.
What does TLD stand for?
Top-level domain: the last label of a domain name, directly under the root of the DNS. In example.com the TLD is com.