From a name to a server: DNS
One loose end. You type shop.example.com, but computers don't actually find each other by name — they use numeric IP addresses like 203.0.113.42. (the Name System) is the web's phone book: before your browser can send a request, it quietly asks DNS to translate the friendly domain name into the numeric address, then connects to that.
┌─────────┐ 1. "what's the IP ┌─────────┐
│ BROWSER │ for this name?" │ DNS │
│ │ ────────────────────▶ │ (phone │
│ │ ◀──────────────────── │ book) │
└─────────┘ 2. "203.0.113.42" └─────────┘
│
│ 3. now connect to that number
▼
┌─────────┐
│ SERVER │ shop.example.com ⇄ 203.0.113.42
└─────────┘
``` You buy a domain, point its DNS records at the server running your app, and from then on the name leads people to your machine. It's a lookup step you'll almost never see, but it's why a memorable name can stand in for a string of numbers.