What Is a Domain Name? Parts, TLDs and How They Work

A domain name is a human-readable name for a location on the internet, like apple.com. It's made of labels separated by dots, read right to left from the top-level domain (.com). You register a domain through a registrar for a yearly fee, and DNS records point it to websites, mail servers and other services.

How it works

www.support.apple.com split into parts: www (host), support (subdomain), apple (domain) and com (top-level domain).

The parts

Top-level domain (TLD): .com, .org, country codes like .de and .jp, and newer ones like .app and .dev.
Second-level domain: the registered name, apple in apple.com.
Subdomains: anything to the left, like support. or www., created freely by the owner.

A fully qualified domain name technically ends with a dot (apple.com.) for the DNS root.

Registration

Registries run each TLD (Verisign runs .com); registrars like Namecheap, Cloudflare or GoDaddy sell names to the public. You rent a domain by the year, and WHOIS / RDAP records show its registrar, creation and expiry dates.

Domain vs URL vs IP

https://support.apple.com/en-us/ is a URL: protocol, domain and path.
support.apple.com is the domain name.
17.253.144.10 is an IP address that DNS returns for a name.

International names

Domains can contain non-Latin characters (例え.jp), encoded behind the scenes as punycode starting with xn--.

Examples

$ whois apple.com | grep -iE 'registrar:|creation date' | head -2
Registrar: Nom-iq Ltd. dba COM LAUDE
Creation Date: 1987-02-19T05:00:00Z

apple.com was registered in 1987, one of the first hundred .com names.

On a Mac

whois example.com shows registration details; dig example.com NS shows which DNS servers are authoritative for it; dig example.com ANY (or separate A, MX and TXT queries) shows what it points to.

See it in the app

LightAtom's connections view shows the full domain name, subdomain included, behind each connection.

Frequently asked questions

What is a domain name?

The readable address of a website or service, like apple.com, which DNS translates into IP addresses.

What is the difference between a domain and a URL?

A URL is a full address including protocol and path (https://apple.com/mac/). The domain is just the name part (apple.com).

Do I own my domain name?

You rent it from a registrar for as long as you keep renewing. If it expires, someone else can register it.

What is a subdomain?

A name under your domain, like blog.example.com, which you can create freely and point anywhere.