How the web works

You use the web every day, but have you ever wondered what actually happens when you type an address and press enter? In this lesson we'll follow that journey from start to finish. You don't need to remember every detail. The goal is to have a rough picture in your head, because it makes everything else in this pathway easier to understand.

There are two main characters in this story.

The browser is the program you use to visit websites. Chrome, Firefox, Safari and Edge are all browsers. Its job is to ask for web pages and then show them to you.

The server is a computer somewhere in the world that stores a website and sends it to anyone who asks for it. It's not a special magic machine. It's just a computer that's always on and always connected to the internet.

When you visit a website, your browser sends a message to a server that basically says "can I have this page, please?" The server sends the page back, and your browser displays it. This back and forth is called a request and a response.

A URL is the address of something on the web. You've typed thousands of them. Let's take one apart:

• https:// tells the browser how to talk to the server. The "s" at the end means the connection is secure, so nobody in between can read what's being sent.
• www.example.com is the domain. It's the name of the website, a bit like the name on a front door.
• /blog/my-first-post is the path. It tells the server which page on the website you want.

Computers don't actually find each other by name. They use numbers called IP addresses, which look something like 93.184.215.14. Since nobody wants to remember numbers like that, there's a system called DNS that works like the internet's phone book. It looks up the domain name and finds the matching number for your browser.

Now let's put the pieces together. Here's what happens when you type an address and press enter:

1. You type https://www.example.com into your browser
2. The browser asks DNS for the IP address of www.example.com
3. DNS answers with the number
4. The browser sends a request to the server at that address
5. The server finds the page and sends it back as a response
6. The browser reads what it got and draws the page on your screen

All of this usually happens in less than a second. Every single time you click a link.

So what exactly does the server send back? Every web page is built from three languages, and each one has its own job.

HTML is the structure and content. It decides what's on the page: headings, paragraphs, images, links and buttons. Think of it as the skeleton of a house.

CSS is the styling. It decides how things look: colors, fonts, spacing and layout. This is the paint, the furniture and the decorations.

JavaScript is the behavior. It decides what happens when you interact with the page, like opening a menu or showing a message when you click a button. This is the electricity that makes the lights turn on.

Here's a tiny taste of each one. Don't worry about understanding them yet, just notice how different they look:

You'll learn all three in this pathway, one at a time and in that exact order. That's the order most developers learn them in, because each one builds on the one before.

Here's something fun: every website you visit sends its HTML, CSS and JavaScript to your browser, which means you can look at it.

In most browsers you can right click anywhere on a page and choose Inspect. A panel opens with something called the developer tools. It looks overwhelming at first, but you're seeing the actual code of the page.

You don't need to understand any of it yet. Just knowing it's there is enough for now. We'll come back to the developer tools later, because they're one of the most useful things you'll learn to use.