How the Web Works
Browsers request pages from servers using HTTP.
About this topic
The World Wide Web is a system of linked pages and resources accessed using a browser over the Internet. When you type a web address, or URL, the browser asks DNS to find the server's IP address, then sends an HTTP or HTTPS request to that server. The server replies with files, usually HTML, CSS and JavaScript, and the browser assembles and displays the page.
This is the client-server model: your browser is the client, and the machine hosting the site is the server. HTTPS adds encryption, shown by a padlock, so others cannot read your data. Status codes tell what happened, such as 200 for success and 404 for page not found. Cookies let sites remember you. Search engines crawl and index pages so you can find them.
For example, loading a news article might need dozens of requests for text, images and scripts. Hyperlinks, invented in the early 1990s by Tim Berners-Lee, connect pages into a web. A common misconception is that the Web and the Internet are the same, or that Google is the Internet. Another is trusting a padlock as proof that a site is honest; it only means the connection is encrypted.
Key ideas
- URL, DNS, HTTP
- HTML, CSS, JavaScript
- Server responds with a page
Quick check
Use cases: where How the Web Works helps
- Homework: review the key idea behind How the Web Works before you start a problem set.
- Exam revision: use the quick check to test whether you can recall How the Web Works without notes.
- Visual learning: play with the interactive lab to see how How the Web Works changes when you adjust its inputs.
- Teaching a friend: explain How the Web Works in your own words, then compare your version with the key ideas.
Computing ideas run phones, search engines, games and the wider internet.
Frequently asked questions
What is How the Web Works?
Browsers request pages from servers using HTTP.
What will I learn in How the Web Works?
URL, DNS, HTTP. HTML, CSS, JavaScript. Server responds with a page.
Is How the Web Works part of Computer Science?
Yes. It is one of 80 Computer Science topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the How the Web Works lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study How the Web Works?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.