zerotoclaude
Module 01/Absolute Zero/Lesson 03

What is the internet?

Servers, browsers, URLs — the internet is just computers talking to other computers.

≈ 8 min read

The internet is not a cloud. It's not a place. It's a giant, boring network of computers that have agreed to send each other messages in a specific format. When you load a website, you're just one computer asking another computer for some files. That's the entire trick.

Two roles: client and server

Every internet conversation has two sides. One side asks for something; the other side answers. The asker is called the client. The answerer is called the server.

When you open a website in your browser, your browser is the client. It sends a request out over the internet to a server somewhere — a physical computer sitting in a data centre. The server reads the request, figures out what to send back, and sends a response. Your browser receives the response, interprets it, and shows you a page.

Note
A "server" is just a regular computer that's been set up to answer requests instead of being someone's laptop. Same kinds of chips, same kinds of storage. The difference is the job.

URLs: addresses for servers

How does your browser find the right server? It uses a URL— that's the thing in the address bar at the top of your browser. Let's pick one apart:

anatomy of a URL
https://zerotoclaude.com/learn/absolute-zero/what-is-the-internet
─────   ─────────────── ────────────────────────────────────────
  │            │                              │
  │            │                              └─ which page on that server
  │            └─ the domain name (which server)
  └─ the protocol (rules for how to talk)

The protocol tells the browser which set of rules to use. https:// is the rules for browsing websites securely. The domain name (zerotoclaude.com) is the human-readable name of the server. The rest is the path — which specific page on that server you want.

How a domain name becomes a real computer

Servers don't actually have names. They have IP addresses — strings of numbers like 104.21.45.12. When you type a domain into your browser, the first thing that happens is a quick lookup through a system called DNS(Domain Name System), which is the internet's phone book. It translates the human-friendly name into the number-based address.

Only then does your browser actually connect to that server and ask for the page. All of this happens in a fraction of a second, every time you click a link.

What you get back

When a server responds to your browser, it sends back text. Not magic. Just text, written in three main languages your browser knows how to interpret:

  • HTML — the structure. Headings, paragraphs, lists, buttons. The skeleton of the page.
  • CSS — the look. Colours, fonts, spacing, layout.
  • JavaScript— the behaviour. What happens when you click, type, scroll. This whole site you're reading is HTML + CSS + JavaScript.

Your browser is doing a tremendous amount of work to turn those three things into the visual page in front of you, but the raw material the server sent was just text.

The internet vs. the web

These get mixed up. The internet is the underlying network — the cables, the routers, the agreement that computers can send packets of data to each other. The web is one particular use of the internet: websites and browsers.

Email, video calls, online games, software updates — those all use the internet too, but they're not the web. Same network, different applications running on top of it.

Why this matters for Claude Code
Claude Code can fetch web pages, talk to servers (called "APIs"), and work with files that came from the internet. Knowing that the internet is just computers asking other computers for text helps demystify what's happening when you read about "API requests" or "HTTP responses" later.
What to take with you
  • The internet is a network of computers sending each other messages.
  • Every web conversation has a client (the asker, usually your browser) and a server (the answerer).
  • A URL is an address. It says which server, and what to ask for.
  • Servers send back text written in HTML, CSS, and JavaScript that your browser turns into a page.
  • The internet is the network; the web is one thing you can do with it.