What is a Top-Level Domain?

Find out how a top-level domain affects your website.

Running a successful business today requires establishing a successful online presence that expands your business beyond the brick and mortar store.

More and more shoppers are looking online to fulfill all of their needs, and if your business isn’t there, you could be missing out on revenue and repeat customers.  Simply registering a domain name is no guarantee of success. It helps to instead understand website domain names are, how they work, the different types of domain names available, and how this technology  plays into your decision of selecting that perfect domain name.

Let’s begin with the question, “What is a top-level domain?”

Online success starts with a great domain; get yours today at Domain.com.

The early days of computers

To understand Top-Level Domains (TLDs), you first need to know how domains function with IP addresses. Think of it like this: every device that connects to the web has an IP address, or a unique electronic signature that distinguishes one device from another. A domain name is the specific text entered after the protocol sign (http://) of a web address. For example, in http://google.com/search/, the domain name is “Google.”

While you’re probably familiar with more prominent domain names, many don’t realize that those names denote the website’s IP address. In fact, each device that connects to the web has an IP signature. When computers were first created, computer scientists invented an ingenious method of communication using numerical strings of 32-bit or 128-bit digits, known as Internet Protocol (IP) addresses. These IP addresses served two purposes:

  1. Network or host identification.
  2. Computer terminal location.

Computers were programmed to follow these sets of protocols in order to locate and communicate with another computer, or to connect to the web. These protocols facilitate this communication, and make it easier for computers to find each other, and send or request information.


In the early days, this numerical system was passable, since there were few computers present on the network. However, as you might imagine, tracking which IP address went to which computer became exponentially more difficult as more computers and systems were added. Organizing and managing these IP addresses wasn’t a feasible or efficient method, since you had to know the exact IP address of any desired website or computer. To simplify this complicated system, computer scientists created the Domain Name System (DNS).

While computers work great with numbers, humans tend to prefer words. We are infinitely better at remembering and categorizing names, as opposed to seemingly random digital sequences. Knowing this, the Domain Name System was proposed as a remedy for the IP address dilemma. This system allows the owner of an IP address to link that numerical string to an unique domain name. So, instead of having to remember, “,” you can simply type in Google.com.

This system was met with resounding enthusiasm. In one fell swoop it improved the following:

  • Made the system easier to navigate.
  • Helped distinguish, organize, track, and monitor IP addresses.
  • Increased the ability to browse and use  the internet.

As a result, in less than three decades the DNS database added billions of names.

How the DNS works:

The DNS database lists all domain names and their corresponding IP addresses. Any time a domain name is entered, the DNS converts that domain name via the DNS server. This server is not one single megaserver, but rather, a sea of servers all over the world, which act in harmony to distinguish one IP address from another.

When a search occurs it filters through the following:

  • The DNS recursor
  • The root name server
  • The top-level domain name server
  • The authoritative name server

As this occurs, there is a system hierarchy and protocol order that facilitates a search through the servers. A top-level domain (TLD) is the highest level in this hierarchical Domain Name System.

The original top-level domains

At their essence, a TLD, also known as a domain extension, is what follows the domain name in a query. The .com in google.com is the top-level domain. These extensions were proposed as methods to help further distinguish and categorize domains. In the early days of the internet, the system was much more rigidly categorized according to these TLDs.

A top-level domain was intended to help classify a feature of a website, such as its purpose, the owner, or the geographical origin. It also multiplied the number of available domain names, since cars.com is not the same as cars.org. To this effect, six original top-level domain names were created. Now that you understand what domain name extensions are, and know how they work, here are some of the most common options available:

  • .com – Short for commercial, dot-coms are the most popular top-level domain in use today. As their names imply, they were initially intended to distinguish commercial organizations. The first three .coms were:
    • Symbolics.com
    • BBN.com
    • Thnk.com

In the early days, .coms were restricted to commercial entities, but by the 90’s these restrictions were lifted, opening the registration floodgates. As the internet continued to grow in use and popularity, dot-coms quickly became the most commonly used top-level domain.

  • .net – Short for network, dot-nets were made for network technology companies like infrastructure companies or internet service providers (ISPs). When they were first introduced, only one domain used the dot-net TLD, Nordu.net, which connected Nordic national research and educational networks. Similar to .coms, the restrictions on .net was not rigidly imposed, which led it to eventually morph into a “general purpose namespace.”
  • .edu – As you likely know, .edu  is a top-level domain meant for American educational institutions, such as colleges or secondary schools. The first three .edus were:
    • University of California Berkeley – Berkeley.edu
    • Carnegie Mellon University – Cmu.edu
    • Purdue University – Purdue.edu

Unlike dot-nets or dot-coms, the dot-edu TLD restriction has been rigidly upheld, meaning you have to be an accredited and registered educational body. While it used to be simply four-year post-secondary institutions, it is now limited to accredited American postsecondary educational institutions.

  • .org – Originally created for organizations which served as nonprofits, with the first being the Mitre Corporation at Mitre.org. This too became a general namespace TLD used by both nonprofit and for-profit organizations.
  • .mil – Created and used by the American military. Dot-mils are top-level domain extensions that are restricted to U.S. military branches:
    • United States Army
    • United States Navy
    • United States Marine Corps
    • United States Air Force
    • United States Coast Guard

As a note, countries outside of America that wish to use .mil, first have to use their country code to distinguish them from the American military branches.

  • .gov – Short for the government, dot-govs, similar to dot-mils, are restricted to American federal governmental agencies and personal use. Dot-govs are used by federal governmental agencies, programs, cities, states, counties, and towns.

Country code top-level domains

Although the internet was created for American governmental use, it was quickly opened to the public, as well as the rest of the world. Since many of these top-level domains were restricted to the American government or military, country code top-level domains (ccTLDs) were added to help distinguish one country from another. Such two-letter country codes are:

  • .au – Australia
  • .ca – Canada
  • .mx – Mexico
  • .uk – Great Britain

Generic top-level domain

Over time, more top-level domains were added to the original list. Presently, there are 21 generic top-level domains at the peak of the domain name system hierarchy. These 21 generic TLDs can be split into four categories:

  • Generic – Domains that are used for general reasons.
  • Generic restricted – Domains that must be used for their intended purposes
  • Infrastructure – Meant solely for aiding the DNS infrastructure. The only TLD within this subcategory is .arpa.
  • Sponsored domains – These can only be utilized by companies or entities tied to these industries including:
    • .aero
    • .asia
    • .cat
    • .coop
    • .edu
    • .gov
    • .int
    • .jobs
    • .mil
    • .mobi
    • .tel
    • .travel
    • .xxx

Generic TLDs

Today, there are more than 1,500 generic extensions available for purchase and worthy of consideration. While your first inclination may be to try and use a .com, such a TLD can sometimes be costly, and many of the domain names linked to that TLD are already taken. The market is oversaturated with millions upon millions of websites. Finding a domain name with a popular TLD that is relevant and helpful to your business can be quite difficult.

Because of this, it may be wise to consider purchasing a newer generic TLD. Benefits of this include:

  • AvailabilityNew domain extensions allow you the opportunity to use your company’s name, or use a word or phrase linked to your industry that would have been taken decades ago with the original TLDs.
  • Cost – If a popular domain name is available, it may cost a lot of money. That same name with a generic TLD extension can cost considerably less money.
  • Creative Names – New domain extensions allow you to be creative with your domain naming process. The domain name can be combined with the generic extension to create a full name, or a clever play on words, that helps the target audience remember the name.
  • Rank on SERPs – Google’s search algorithm has been updated so that domains that do not use a main TLD are not ranked lower for that reason. You don’t need to worry about your rankings on Search Engine Results Pages (SERPs) being affected by this newer gTLD.

Registering a top-level domain

In order to register a domain name with the Internet Corporation for Assigned Names and Numbers (ICANN), you must do so through a registrar, such as Domain.com. You can check if if your perfect domain name and domain extension is available through domain search. You will need to submit the following information when registering:

  • Your domain name
  • Your top-level domain extension
  • Your contact info: first name, last name, email address, phone number, and physical address
  • Your billing info

After receiving this information, Domain.com submits this info to ICANN and the DNS. Once confirmed, you can quickly setup your domain and build a website.

Top-level domains help customers find your business online

The creation of the DNS opened the internet to the world, increasing its accessibility and usability. Top-level domains helped to further simplify and categorize the various domain names, and newer generic TLDs increased the number of possible domains. As a result, you can be assured that the perfect domain and top-level domain combination is out there, just waiting for you.

Online success starts with a great domain; get yours today at Domain.com.

Kristin Crabb
Kristin Crabb

Content Marketing Strategist working in the digital marketing industry. Skilled in SEO-focused content creation, keyword research and competitive analysis, interactive content, web content optimization, and landing page creation.

Kristin Crabb
Kristin Crabb

Content Marketing Strategist working in the digital marketing industry. Skilled in SEO-focused content creation, keyword research and competitive analysis, interactive content, web content optimization, and landing page creation.