Web Basics

Web Basics — CodeSensei Teaching Module

HTML

• Analogy: HTML is the skeleton of a webpage. It defines the structure — where the heading goes, where the paragraph goes, where the image goes. Like the blueprint of a house showing where rooms are.
• Key insight: HTML uses "tags" that come in pairs: <tag>content</tag>. The tag tells the browser what KIND of content it is.
• Key tags to teach:
  • <h1> to <h6> — headings (h1 is the biggest, like a newspaper headline)
  • <p> — paragraph (a block of text)
  • <a> — link (a door to another page)
  • <img> — image (a picture on the wall)
  • <div> — container (a box that groups things together)
  • <form> — form (like a paper form you fill out)
  • <button> — a clickable button
• Quiz idea: "If you wanted to add a clickable link to Google, which tag would you use?"

CSS

• Analogy: CSS is the paint, wallpaper, and furniture of the house. HTML says "there's a heading here," CSS says "make it blue, centered, and 32px big."
• Key insight: CSS works by SELECTING an HTML element and then STYLING it. It's always: "who are you targeting?" + "what should they look like?"
• Key concepts:
  • Selectors (which elements to style)
  • Properties (what to change: color, size, position)
  • Values (the specific setting: red, 16px, center)
  • Classes (reusable style labels, like "VIP" or "highlighted")
• Quiz idea: "If the text is too small, which file would you change — the HTML or the CSS?"

How Browsers Work

• Analogy: A browser is like a translator + artist. It reads your HTML (the instructions), applies your CSS (the design specs), and paints the result on screen.
• Key insight: When someone visits your site, the browser downloads your files and assembles them in real-time. That's why you see the page "load."
• Teaching flow: User types URL → Browser requests files from server → Server sends HTML/CSS/JS → Browser assembles and displays the page

The Relationship

HTML = Structure (what's on the page)
CSS  = Style (how it looks)
JS   = Behavior (what it does)

Think of it as: HTML is the house frame, CSS is the interior design, JavaScript is the electricity and plumbing that makes things work.