What Is a Domain Name

A domain name is the human-friendly address of a website, like `example.com` — it exists because, as the how-the-internet-works topic explained, computers actually find each other using numeric IP addresses, which are hard for people to remember, so a domain name is the memorable name that stands in for one of those numbers. The connection between the two is made by DNS, the Domain Name System introduced in the internet and URL topics, which acts as the internet's phone book: when you use a domain name, DNS looks up the IP address it points to so the request knows where to go. Reading a domain name is easiest from right to left, because it is built in order of decreasing generality. The rightmost part is the top-level domain (TLD) — the `.com`, `.org`, `.net`, or a country code like `.uk` — the broadest category. To its left is the part someone actually registers, so in `example.com` the word `example` is the registered name, and `example.com` together is the registered domain a person or company owns. Anything further to the left is a subdomain, a subdivision the owner controls freely: in `blog.example.com` or `www.example.com`, the `blog` and `www` are subdomains the owner created under their domain — which is why the owner of `example.com` can make as many subdomains as they like without registering anything new. This right-to-left reading is also the phishing-defense skill from the staying-safe-online and URL topics: because the registered domain is the two parts just to the left of the final slash's domain portion, `www.paypal.com.secure-login.example` is really owned by `example`, not PayPal, no matter how trustworthy the left side looks. Owning a domain works by registration, not purchase forever: you lease a domain name through a company called a registrar for a period, usually yearly, and as long as you keep renewing it, it is yours and no one else can use it — let it lapse and someone else can register it. Domain names also matter beyond websites: the email addresses from the how-email-works topic use the same domains (the part after the `@`), which is how mail finds the right servers. The simple takeaway is that a domain name is a memorable stand-in for a numeric address: DNS translates the name to the number, the name is structured right-to-left from broad TLD to specific subdomain, you lease it from a registrar, and reading it correctly — especially spotting the real registered domain — is both how the system routes your request and how you tell which site you are truly dealing with.