The top-level domain (TLD), sometimes called the internet domain extension, is the very last section of an internet domain name, located after the last dot, to help form a fully qualified domain name (FQDN).
For example, the top-level domain of lifewire.com and google.com are both .com, but the TLD of wikipedia.org is .org.
What Is the Purpose of a Top-Level Domain?
Top-level domains serve as an instant way to understand what a website is about or where it's based.
For example, seeing a .gov address, like in www.whitehouse.gov, will immediately inform you that the material on the website is centered around government.
A top-level domain of .ca in www.cbc.ca indicates something about that website, in this case, that the registrant is a Canadian organization.
There’s also a side effect TLDs, which is that because there are several options, multiple websites can use the same name but be totally different sites or companies. Apart from the last bit where the TLD sits, the URLs might be identical.
For example, lifewire.com is this website but lifewire.org is another with the same name but different TLD, so they're actually completely different websites. The same is true for lifewire.edu, lifewire.net, and lifewire.news, among others (many are listed below).
It's for this reason that some companies will register multiple TLDs so that anyone going to the other, non-primary URLs, will still land on the company's website. For example, google.com is how you reach Google's website, but you can also get there through google.net. However, google.org is a totally different website.
What Are the Different Top-Level Domains?
A number of top-level domains exist, many of which you've probably seen before.
Some TLDs are open for any person or business to register, while others require that certain criteria be met.
Top-level domains are categorized in groups: generic top-level domains (gTLD), country-code top-level domains (ccTLD), infrastructure top-level domain (arpa), and internationalized top-level domains (IDNs).
Generic Top-level Domains (gTLDs)
Generic top-level domains are the common domain names you're likely most familiar with. These are open for anyone to register domain names under:
- .com (commercial)
- .org (organization)
- .net (network)
- .name (name)
- .biz (business)
- .info (information)
Additional gTLDs are available that are called sponsored top-level domains, and are considered restricted because certain guidelines must be met before they can be registered:
- .int (international): Used by international organizations for treaty-related purposes, and requires a United Nations registration number
- .edu (education): Limited to educational institutions only
- .gov (government): Limited to U.S. governmental entities only
- .mil (military): Limited to the U.S. military only
- .jobs (employment): Must be registered under the legal name of a company or organization
- .mobi (mobile): Might have to adhere to mobile-compatible guidelines
- .tel (Telnic): Limited to hosting related to contact information, not websites
There are also these reserved TLDs that are meant for testing and documentation purposes:
- .test: Recommended for use in testing of current or new DNS related code.
- .example: Recommended for use in documentation or as examples.
- .invalid: Intended for use in online construction of domain names that are sure to be invalid and which it is obvious at a glance are invalid.
- .localhost: Has traditionally been statically defined in host DNS implementations as having an A record pointing to the loop back IP address and is reserved for such use.
Country Code Top-level Domains (ccTLD)
Countries and territories have a top-level domain name available that’s based on the country’s two-letter ISO code. Here are some examples of popular country code top-level domains:
- .us: United States
- .ca: Canada
- .nl: Netherlands
- .de: Germany
- .fr: France
- .ch: Switzerland
- .cn: China
- .in: India
- .ru: Russia
- .mx: Mexico
- .jp: Japan
- .br: Brazil
The official, exhaustive list of every generic top-level domain and country code top-level domain is listed by the Internet Assigned Numbers Authority (IANA).
Infrastructure Top-Level Domains (arpa)
This top-level domain stands for Address and Routing Parameter Area, and is used solely for technical infrastructure purposes, such as resolving a hostname from a given IP address.
Internationalized Top-Level Domains (IDNs)
Internationalized top-level domains are TLDs that are displayed in a language-appropriate alphabet.
For example, .рф is the internationalized top-level domain for the Russian Federation.
How Do You Register a Domain Name?
Internet Corporation for Assigned Names and Numbers (ICANN) is in charge of managing top-level domains, but registration can be done through a number of registrars.
Some popular domain registrars you may have heard of include GoDaddy, 1&1 IONOS, Network Solutions, Namecheap, and Google Domains.
If you're looking to start a new website, keep in mind that there are also ways to get a free domain name.
Finding New TLDs
If you follow the IANA list above, you’ll find that there are numerous TLDs you’ve never heard of, .GOOGLE being one that you might not see very often.
Google Registry is one place where you can see some of the TLDs they’re working on releasing so that new websites can start ending in those letters, too.
Upcoming and newly released TLDs are also available on major domain registrar websites like Namecheap and GoDaddy.
TLD shouldn't be confused for TeleDisk disk images that also use this abbreviation, or TLDR ("too long, didn't read").