What is a Domain Name?

Summary 

Domain names are a key part of the Internet Infrastructure. They provide a human-readable addres for any web server available on the Internet.

Any Internet-connected cmputer can be reached through a public IP Address, either an IPv4 address (e.g., 192.0.2.172) or an IPv6 address (e,g., 2001:db8:8b73:0000:0000:8a2e:0370:1337).

Computers can handle such addresses easily, but people have a hard time finding out who is running the server or what sercice the website offers. IP addresses are hardd to remeber and might change over time.

Hierarchy and Anatomy of a Domain Name

Domain names are organize in a hirerachical structure, typically read from right to left, with each section seperated by a dot:

• Top-Level Domain (TLD): This is the extension at the end of the address (e.g., .com, .org, .net). TLDs categorize webistes by purpose, industry, or geography (such as .uk for the United Kingdom)
• Second-Level Domain (SLD): Located directly to the left o the TLD, this is usually the most indentifiable part of the address, representing a brand, commpany, or individual (e.g., google in google.com).
• Subdomain (Third-Level Domain): An optional prefix added to the root domain to organize specific sections of a website (e.g., blog in blog.example.com or www in www.example.com).

Domain Name vs. URL

It is common to use the terms interchangeably, but a domain name is only one component of a Uniform Resource Locator (URL). While the domain name identifies the server, the URL provides the specific directions to a particular resource. For example, in https://example.com/about-us:

• https:// is the protocol.
• example.com is the domain name.
• /about-us is the path to a specific page.

Technical Rules and Governance

Domain names must follow strict technical specifications defined by ICANN and relevant standards:

• Character Set: They primarily use the "LDH" set (Letters, Digits, and Hyphens).
• Length Limits: Each section (label) can be 1–63 characters long, and the entire domain name cannot exceed 253 characters.
• Case Insensitivity: Example.com is functionally identical to example.com.

The management of domain names involves three main parties: the Registry (the organization that manages the database for a TLD), the Registrar (the accredited company that sells registrations to the public), and the Registrant (the person or entity that leases the name for a set period). All of these are coordinated globally by ICANN.