How a page is made
What a web page is made of: HTML says what each part is, CSS how it looks, and JavaScript how it behaves, all inside a browser that brings its own toolbox. You won't write any of it, but knowing which layer does what lets you judge a mockup, a quote or a bug report, and ask for the fix in the right place.
- Structure and meaningHTML labels what each part of a page is, and screen readers, keyboards, search engines and AI agents rely on those labels rather than on the look.
- Look and layoutStyle rules shared by every page set the look, so a well-built site changes everywhere from one place and adapts to every screen and to each visitor's settings.
- BehaviourScripts wait for events and change the page while it's open, and keeping the data in one place, with the screen redrawn from it, is what keeps a page consistent and what frameworks automate.
- When it breaksA page that relies on scripts can go blank, give wrong answers with no error, or run code a visitor typed in, and the browser's error messages show where to look.
- The browser's toolboxThe browser can fetch, remember, copy, watch, draw and animate on its own, but anything shared between visitors, secret or enforced needs a server, and a page has to be served, not just opened.