Quick Answer
The internet is billions of computers connected to each other through physical cables, fibre, and wireless links. They communicate by following shared rules called protocols. When you visit a website, your computer sends a request across this network and receives a response, usually in under a second.
An industrial cable under tension with red sparks flying at the connection point: the moment data crosses a boundary between two systems.
The internet is billions of these connections firing simultaneously. Every request you send travels through physical cables, routers, and servers before the response reaches you.

It is a physical thing

The internet often gets described as a “cloud” or something abstract. It is not. It is an enormous physical infrastructure:

  • Undersea cables running along ocean floors connect continents. You can see them all at submarinecablemap.com . There are hundreds of them carrying virtually all international internet traffic.
  • Data centres, buildings full of servers, store most of the world’s websites and data. A single large data centre can contain hundreds of thousands of servers.
  • Your router at home connects your devices to your internet provider’s network, which connects to larger networks, which eventually reach those data centres.

When you load a video from another country, data is physically travelling through cables, including along the ocean floor, and reaching you in under 100 milliseconds.

The internet vs the web

These two terms are not interchangeable.

The internet is the global network: the physical cables, routers, and protocols that allow computers to communicate. It is infrastructure.

The web (World Wide Web) is one service that runs on top of the internet. It is the system of linked pages you access with a browser, built on HTTP. Tim Berners-Lee proposed it in 1989 and made it publicly available in 1991.

Email, video calls (Zoom, FaceTime), file transfers (FTP), and SSH connections also run over the internet, but they are not “the web”. The web is the specifically browser-based part.

How computers find each other: IP addresses and DNS

Every device on the internet has a numerical address called an IP address. IPv4 addresses look like 142.250.74.46. IPv6 addresses (the newer standard) are longer. These numbers identify where on the network a device is located.

You do not type IP addresses. You type domain names like google.com. This works because of DNS (Domain Name System), a distributed global database that maps human-readable names to IP addresses. More: How DNS works, Cloudflare

When you type github.com:

  1. Your browser checks its local DNS cache
  2. If not found, asks your router, which asks your ISP’s DNS server
  3. If still not found, the query reaches an authoritative DNS server for .com domains
  4. The final answer, an IP address like 140.82.114.3, travels back to your browser

The whole process takes milliseconds. There is even a comic explaining how DNS works if you want to go deeper.

DNS resolution: how a domain name becomes an IP address
You type github.com Human-readable domain name
→
Browser cache Known IP? If visited recently, answer is cached locally
→
ISP DNS Recursive resolver Asks root → .com → github.com authoritative servers
→
Answer 140.82.114.3 IP address returned; browser connects here via TCP

How data travels: packets

Data sent over the internet does not travel as one continuous stream. It is broken into small chunks called packets, typically a few kilobytes each. Each packet travels independently through the network and is reassembled at the destination.

This is why:

  • Videos buffer when packets are delayed or lost
  • Your download can use multiple paths simultaneously for speed
  • A single cable failing does not bring down the internet (packets reroute)

The rules for how packets are addressed and routed are defined by TCP/IP, the foundational protocol suite of the internet. TCP guarantees that packets are reassembled in order and re-requested if lost. UDP, the other main protocol in the suite, skips that guarantee for speed and is used in video calls and online games where a dropped frame is better than a delayed one. More: TCP/IP, Wikipedia

HTTP and HTTPS: the language of the web

When your browser talks to a web server, they use HTTP (HyperText Transfer Protocol). HTTP defines how requests are structured and how responses are returned. More: HTTP, MDN

A basic HTTP exchange looks like:

Request:  GET /index.html HTTP/1.1
          Host: example.com

Response: HTTP/1.1 200 OK
          Content-Type: text/html
          [the HTML of the page]

HTTPS is HTTP with TLS encryption. The S stands for Secure. The data is encrypted end-to-end, the server’s identity is verified via a certificate, and no one in the middle can read or alter it. Any site handling logins, payments, or personal data must use HTTPS. Browsers now flag HTTP-only sites as “Not Secure”.

HTTP status codes tell you what happened: 200 OK (success), 404 Not Found, 500 Internal Server Error, 301 Moved Permanently. You will see these when building apps or debugging.

What a website actually is

A website is a collection of files stored on a server:

  • HTML, the structure and content
  • CSS, the visual design and layout
  • JavaScript, the interactive behaviour

When you visit a URL, your browser sends an HTTP request to the server hosting those files. The server sends them back. Your browser parses them and renders the page you see. A single page load can involve dozens of individual requests, for the HTML, then each image, stylesheet, and script.

How this shapes everything you build

Every web application you build or describe to an AI tool operates on these same fundamentals. When you hear:

  • “Make an API call”, send an HTTP request to a server and handle its response
  • “Deploy to the cloud”, put your code on a server with an internet-facing IP address
  • “CORS error”, a browser security rule blocking cross-origin HTTP requests
  • “SSL certificate”, the certificate that enables HTTPS

These all make more sense knowing the underlying model: computers sending structured messages to each other over a global physical network.

Further reading

What’s next

Next: What is Code? , the instructions that tell computers what to do.