What is a Top-Level Domain (TLD)?

The internet contains more than 50 billion web pages, and that number increases every day. So, when you clicked on the link to view this article, how did your browser figure out so quickly where to find it?

The answer is through the Domain Name System (DNS). This article will explore top-level domains, which are one of the fundamental parts of the DNS and the internet.

What is a Top-Level Domain (TLD)?

For most internet users, a top-level domain (TLD) is the rightmost part of a domain name. For instance, for the website 800.com, “.com” is the TLD.

If you think of a domain name as a US physical address, a TLD is similar to a country. Other levels of the domain name provide more specific information that could correspond to the state, city, and street of a physical address.

Who Keeps Track of TLDs?

All TLDs are actively maintained by the Internet Assigned Numbers Authority (IANA), which is a standards organization owned by the Internet Corporation for Assigned Names and Numbers (ICANN). Together, IANA and ICANN are responsible for all domains and IP addresses throughout the internet.

[link bolded text ICANN to unpublished article: What is ICANN?]

What Kinds of TLDs Are There?

There are three recognized types of TLDs: generic TLDs, country-code TLDs, and infrastructure TLDs.

Generic TLDs

Most people are familiar with generic TLDs (gTLDs), which can be used anywhere and by anyone in the world. These include the most well-known TLDs, such as:

• .com
• .net
• .org
• .info

Country Code TLDs

In addition to generic TLDs, there are TLDs that are reserved for specific countries or territories. Examples of these country-code TLDs (ccTLDs) include:

• .us: United States
• .ca: Canada
• .mx: Mexico
• .cn: China
• .uk: United Kingdom

Each country has its own assigned two-letter ccTLD that uses Latin characters (letter A to Z). Starting in 2018, many countries began adopting internationalized ccTLDs that use their own writing systems such as Chinese, Arabic, and Cyrillic.

Infrastructure TLDs

The third type of TLD is used to support and manage critical internet operations. Infrastructure TLDs such as .arpa are rarely used directly by the general public.

Can You Use Any TLD for Your Website?

It depends. While some TLDs are truly unrestricted to anyone in the world, many are limited only to eligible registrants.

Generic Restricted TLDs

ICANN can designate a TLD to be a generic restricted TLD (grTLD). These TLDs are open to anyone in the world that meets specific requirements. There are three major grTLDs in use today:

• .biz: Registrants must use the domain name for business or commercial purposes.
• .name: Registrants must be individuals.
• .pro: Registrants must provide professional services and be licensed by a government-recognized certification or licensing authority.

Sponsored TLDs

In addition to managing generic restricted TLDs, ICANN recognizes sponsored TLDs (sTLDs). The restrictions for sTLDs aren’t set directly by ICANN, but rather by other entities and organizations. Sponsored TLDs include:

• .edu: Sponsored by Educause and restricted to higher-learning institutions in the US
• .gov: Sponsored by the US General Services Administration and restricted to federal, state, and local government entities in the US
• .mil: Sponsored by the US government and restricted to US military entities
• .aero: Sponsored by the International Society of Aeronautic Telecommunications (SITA) and restricted to entities in the aviation industry

Country Code TLD Restrictions

Each country can set its own requirements and restrictions on using its ccTLD. In many cases, registrants must be citizens or have some sort of presence in that country. Here are a few examples of ccTLD restrictions:

• .us: The registrant must be a US citizen, a legal resident, or a foreign entity with a US presence.
• .ca: The registrant must comply with Canadian Presence Requirements.
• .cn: The registrant must be a local company in China or an individual with a Resident Identity Card.
• .de: The registrant must provide a valid German postal address.

On the other hand, some ccTLDs are unrestricted to anyone. Here are some well-known examples of popular ccTLDs used around the world:

• .io: The British Indian Ocean Territory ccTLD is often used by startups and tech companies.
• .ms: The Montserrat ccTLD is famously used by Microsoft, the New York Times, and in Mississppi.
• .la: The Laos ccTLD is also used as an unofficial domain for Los Angeles.

How Does Your Browser Use TLDs?

TLDs are the highest level of the Domain Name System (DNS), which is the phonebook of the internet. All web content is stored in servers located all around the globe. The TLD, together with the other parts of the DNS, helps your browser locate the specific server that stores the webpage you want to view.

How does it work?

Suppose that you’re visiting 800.com. When you type the web address into your browser, your computer first contacts a special server called a root nameserver. There are 13 root name servers around the world, and they contain information about where to find TLD servers. In this case, the root nameserver would direct your browser to find a .com TLD nameserver.

Next, your browser communicates with the .com TLD nameserver, which stores IP addresses for all websites that use the .com TLD. From there, the .com TLD nameserver directs your browser to the IP address associated with 800.com.

Why Are TLDs Important?

TLDs Make It Easier to Navigate the Internet

When you type in a web address, your browser uses the TLD and other parts of the domain name to retrieve an IP address. It’s actually the IP address that directs your browser to the website.

So, why take the extra step of using TLDs?

TLDs and domain names were created so that people could easily navigate the internet. It’s much easier to remember a TLD and domain name than a long list of numbers. Without TLDs, people would need to type in a long list of numbers for every website they wanted to visit.

TLDs Help Detect Fraud

Restricted TLDs also help people identify fraudulent websites. For instance, an organization that claims to be part of the government could be fraudulent if its website doesn’t use a .gov TLD. Similarly, emails that claim to come from a US bank are probably fraudulent if the TLD doesn’t match the one used on the bank’s main website.

TLDs Helped Make the Internet What it Is Today

Most people don’t think much about TLDs when they use the internet. And, in a way, this is a good thing — TLDs were developed to make the internet much more intuitive. But that doesn’t make TLDs any less important. Without TLDs, using the internet would be much more challenging or even practically impossible.