Browsers
🏠The everyday picture
A browser is a very fast reader and painter. It receives instructions (HTML), a style guide (CSS) and stage directions (JavaScript), then paints a page and keeps it responsive while you click and type.
📘What it really is
- A browser (Chrome, Edge, Firefox, Safari) requests files from servers and turns them into the page you see.
- A page is usually made of:
- HTML: the structure and content (headings, paragraphs, images, links);
- CSS: the look (colours, fonts, layout);
- JavaScript: the behaviour (menus that open, forms that check input, buttons that do things);
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images, fonts and other files.
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One page can need dozens of separate requests: one for the HTML, then more for each stylesheet, script and image.
- Every browser has developer tools to inspect all this. You'll use them constantly from Level 2 on.
🖱️Try it
Open any website, right-click on a heading and choose Inspect. You'll see the HTML for that heading and, beside it, the CSS that styles it. Change the text in the HTML panel: the page changes on your screen only. Refresh, and it's back. You can't break the real site this way.
✅Quick check
Which part of a page controls its colours: HTML, CSS or JavaScript?
Show the answer
CSS.
You edited a website's text in Inspect and it changed. Did you change the website for everyone?
Show the answer
No. You only changed your browser's copy. Refreshing reloads the real page from the server.