top level domain

What Is A Top Level Domain?


Finding websites wasn’t always as easy as it is now. In the early days of the internet, every website just had a string of numbers that served as its address. Anyone who wanted to visit a specific site had to know the exact numbers that related to type or they would never find it. This was way before we had search engines.

A string of numbers (known as IP addresses) are still used to identify websites, but top level domains (TLDs) have been in use since 1984 to make finding sites a lot easier. When a TLD, or domain extension, is combined with a domain name, you get something that looks like this:

The TLD is the .com in the address above. Without the domain name and the TLD, we would have to type the IP address for the website listed above in a browser to reach the same website. Since that site’s IP address is, you can see how that wouldn’t be easy to remember, and even if you did, could you imagine trying to memorize multiple IP addresses? Domain names are much easier.

What is a TLD?

If you’re looking for a specific TLD definition, this is a very basic way to describe it: A top-level domain is a domain suffix. It is what follows a domain name. Since that may not provide enough explanation, it’s better to consider why TLDs are needed in order to better understand what they are.

Once it was decided that domain names would be used to make searching for websites on the internet easier, the next problem to solve was how to organize them all. Top level domains were the answer.

The first TLDs were categorized according to country, category or multi-organization. For example, .com is short for commercial and .org represents nonprofit organizations. A popular one to use now is .io, which stands for Indian Ocean.

What is the purpose of a TLD?

Put simply, it’s a way to organize the internet so humans can locate what they need and generally identify the type of organization that owns a website before visiting it. For example, when you see a .org TLD, you expect the website to not be exclusively for commercial purposes. And if a website uses .gov, you already know before visiting it that a government agency is running the site.

However, this doesn’t mean you must follow these guidelines. There’s nothing stopping someone from using a .com TLD for charitable purposes or a .org for commercial ones, but there are limitations for some, such as .gov and .mil TLDs. They cannot be purchased since they’re reserved for government agencies.

The original list of TLDs

As mentioned above, the first TLDs were all created to organize domain names according to their purpose. You can see how they were categorized in the list below:

.govGovernment agencies
.intIntergovernmental organizations
.milU.S. military
.netInternet service providers

Since this original list was made, more than 1500 other TLDs have been created.

How TLDs relate to the structure of the internet

The Internet Corporation for Assigned Names and Numbers (ICANN) controls who can create and manage TLDs. It oversees the Domain Name System (DNS), which is the framework for how domain names operate.

A subsidiary of ICANN called the Internet Assigned Numbers Authority (IANA), manages the DNS Root Zone. This is important to know because the Root Zone Database consists of only 13 clusters of servers. These servers store all TLDs and domain names.

This means that when a search engine or your browser finds a website, it has either accessed one of these servers directly or connected to a database that has previously connected to them.

Types of TLDs

IANA uses the following system to categorize TLDs:

Infrastructure top-level domain (ARPA): This consists of one domain, the Address and Routing Parameter Area, and IANA uses it for engineering purposes.

Generic top-level domains (gTLD): These are TLDs with three or more characters, including .com and .org.

Restricted generic top-level domains (grTLD): These domains are run by official ICANN accredited registrars.

Sponsored top-level domains (sTLD): These domains are proposed and sponsored by private agencies or organizations that establish rules to restrict eligibility to use them.

Country-code top-level domains (ccTLD): These are two-letter domains created for countries or territories.

Internationalized country code top-level domains (IDN ccTLD): These are ccTLDs that use non-Latin character sets, such as Chinese and Arabic.

Test top-level domains (tTLD): These domains are for testing purposes.

Country TLDs

Of all the types of TLDs, the two-letter country TLDs are among the more interesting. It’s become popular to use them to create interesting one-word domain names such as Since many words in the english language end in -ly, it’s a fun way to make a domain name stand out.

However, before selecting a TLD with two letters, it may be worth looking into the country it represents. The -ly TLD is for Libya, which means it’s possible for its government to restrict the types of sites and the content they post on that domain. It works this way for all country TLDs, so be mindful of this before purchasing them for your website.

Top level domains are how the internet is organized. Without them, we’d be stuck memorizing IP addresses. There’s much more to how the internet operates than what’s listed here, but understanding TLDs is a good place to start the journey.