The three languages

Every webpage is built from three languages, and each has exactly one job:

• HTML is the structure — what's on the page. Headings, paragraphs, images, buttons.
• CSS is the design — what it looks like. Colours, fonts, spacing, layout.
• JavaScript is the behaviour — what it does. Reacting to clicks, changing things, checking answers.

They work together but never do each other's jobs. Keeping them separate is what makes websites possible to build and change.

Think of building a house:

• HTML is the walls, rooms and doors — the structure that holds everything. A house with only this is bare but standing.
• CSS is the paint, furniture and lighting — it changes nothing about where the rooms are, only how they look.
• JavaScript is the electrics and plumbing — the things that respond when you flip a switch.

You can have a house with no paint. You cannot have paint with no house. HTML comes first, always — which is why you'll learn it first.