A domain name is an alphanumeric string typed into a piece of client software, such as a web browser’s URL bar, in order to access a specific website or network. For example, the domain name for Superb Digital is: superb.digital

Websites and networks are realms of “administrative autonomy” hosted on web servers that are connected to the internet. As of the time of writing, there are nearly 4.3 billion such realms, so for identification purposes, they are assigned numerical labels known as Internet Protocol addresses (IP address). Superb Digital’s IP address looks like this:

Because human internet users are unlikely to remember numerical sequences, website owners are able to define a string of text that maps to their IP address via a process called Domain Name System (DNS) lookup. This string of text is the domain name.

When a domain name is entered into a browser, the software sends a lookup request to the DNS, which locates the hostname of the web server associated with the domain. The web server then fetches the requested web page and sends this data back to the browser.

Domain names are organised into subordinate levels (subdomains). Each level is delineated by a dot and moves from general to specific when read right-to-left.

  • The top-level domain (TLD) is found to the right and includes familiar generic top-level domains (gTLDs), such as .com and .org, country code domains (ccTLDs) such as .uk and .ie, and sponsored top-level domains (sTLDs) such as .gov and .edu.
  • Second level domains and third-level domains are found below the TLDs in the DNS hierarchy. These lower-levels are the parts that are typically reserved by internet users who run websites or connect local area networks to the internet.

For example, Amazon’s UK domain name has three levels:

  • .uk is the ccTLD (general)
  • .co is the 2LD (indicating a company)
  • amazon is the 3LD (specific)

The Internet Corporation for Assigned Names and Numbers (ICANN) administers the DNS, and gives permission to companies called Domain Name Registrars to sell domain names. Users can register domain names via a domain registrar.