Top level domain and co.: the big domain glossary part 1

Creating your own domain can be a daunting process to someone who is not familiar with all the terminology. This post seeks to shed some light on this often opaque language by providing a glossary of terms and acronyms that can be helpful to understand.


The internet is based on IP addresses which are used by a computer to find a website on the internet. Therefore, every website has a unique digit sequence known as an IP address. However, when people around the world are trying to find your website they will commonly use a memorable domain name such as rather than a string of numbers which are difficult to remember.

The DNS or Domain Name System is an internet service that translates your memorable domain name into its assigned IP address. This is so that a computer can locate your website when somebody searches for it using the domain name.

The Domain Name System is essentially an electronic address system that consists of the Top Level Domain (TLD), the Second Level Domain (SLD) and the Third Level Domain (Subdomain):

Top Level Domain (TLD)

The Top Level Domain is the last part of the domain name. These endings can be divided into three groups:

  • First there are the generic Top Level Domains (gTLD), that end in for example .com, .org. or .net.
  • Secondly, there are country code Top Level Domains (ccTLDs). More than 200 country codes belong to these ccTLDs and they usually end in for example .us for the United States, .fr for France or .es for Spain.
  • Thirdly, there are the new Top Level Domains (nTLDs) which have been gradually introduced since 2013. These include short and easy-to-remember domain endings like .xyz, .shop or .newyork.

Second Level Domain (SLD)

The Second Level Domain is the unique name in front of the TLD. This can be the name of a person, institution or company ( Since it is unique to a specific entity, SLDs have name and trademark protection.

Third Level Domain

The Third Level Domain is also known as the Subdomain. It usually provides structure to an organization’s website. This can be useful if a website needs to organize pages into branches, departments or different languages. A typical example for a Third Level Domain blog or company news section can be: or

Did you know? The most commonly used subdomain is the internet standard www (World Wide Web).

Country Code TLD

The ccTLDs refer to countries as well as regions and consist of a two letter country code which represent the country. All together there are more than 200 country codes. Take a look at the 1&1 Digital Guide to find out more about ccTLDs.

Generic TLD

Generic Top Level Domains (gTLD) are divided into sponsored (sTLD) and unsponsored Top Level Domains (uTLD). A sponsored TLD means, the TLD is controlled, proposed and financed by a company or organization. Examples of this include .gov and .mil which are exclusively for the use of the US government and affiliated US military institutions. However, the most widely used are the unsponsored generic TLDs, which are administrated by ICANN and the Internet Society. The most common unsponsored TLD is .com and has been registered over 127 million times by users around the world.

CNOBI Domains

This acronym consists of the first letters of the five generic domain endings .com, .net, .org, .biz and .info. They are specialized in certain sectors but can be registered without restrictions.

  • .com (= commercial): for companies and commercial enterprises
  • .net (= network): for (computer) networks
  • .org (= organization): for non-profit or commercial organizations
  • .biz (= business): for websites with a business background (e.g. companies, freelancer or professionals)
  • .info (= information)for website information


The “old” Top Level Domains (gTLDs and ccTLDs) are becoming more limited in the range of available web addresses because a lot of them have already been taken. As a result of this oversubscription, new Top Level Domains (nTLDs) have been introduced: These new domain endings offer users a new opportunity to register short and concise web addresses, which also have a high recognition value. There are nTLDs that refer to a local area (.nyc, .miami, .vegas), to activities and interests (.photography, .sport, .cloud) or for specific sectors (.restaurant, .construction, .car). Please take a look at our website for a complete list of all available nTLDs such as .london, .scot, .wales, .cymru and .ltd.

In the second part of this series we will tell you all you need to know about the Domain Name System (DNS), the meaning of URL and root servers.

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1 comment1

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  1. April 12, 2017 at 3:59 am | by Greg

    Great blog. I really enjoyed it and learned a lot.