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Beginner · 5h 32m · 24 lessons

Web Application Basics

How the web works, from the request that starts it all to the HTML and CSS of a page.

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What you'll learn

  • ✦Explain what happens from typing a URL to getting a page back: DNS, the request, the method and the status code
  • ✦Decide which jobs belong in the browser and which on the server, and say why
  • ✦Write a clean, semantic HTML page with headings, links, images and a labelled form
  • ✦Style and lay out a page with CSS selectors, the box model, flexbox and media queries
  • ✦Explain how a browser turns HTML and CSS into pixels, and what slows that down
  • ✦Build a small interactive feature with JavaScript events, DOM changes and fetch
  • ✦Diagnose page problems with DevTools and put a page live on a domain with HTTPS
  • ✦Check a page for basic accessibility and speed problems, and fix the biggest ones

Part of these career paths

Certification projects

Build 4 projects to earn your certificate

Hands-on work that proves you can apply what you learned — part of the certificate requirements.

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Syllabus

Module 1 · 1h 4m
How the web works Free
What you'll be able to do
  • Can trace what happens from typing a URL to seeing a page: the DNS lookup, the request and the response
  • Can take a URL apart and say what each part tells the browser and the server
  • Can pick the right HTTP method for a task and say who has to fix a 4xx or a 5xx
  • Can decide which jobs belong in the browser and which must stay on the server
Module 2 · 1h
Structure with HTML Locked
What you'll be able to do
  • Can write a valid page skeleton and say what belongs in the head and what in the body
  • Can choose semantic tags and heading levels that say what each part of a page is
  • Can add links, images with useful alt text, and a labelled form that sends every field
Module 3 · 1h 8m
Style with CSS Locked
What you'll be able to do
  • Can write CSS rules with tag, class and id selectors, and predict which rule wins when two clash
  • Can work out a box's real rendered width from its padding, border and margin
  • Can lay out a row or column with flexbox, and swap it for phones with a media query
  • Can spot a silent CSS typo in a live editor instead of assuming the tool is broken
Module 4 · 44m
How it comes together Locked
What you'll be able to do
  • Can put the browser's steps from HTML and CSS to pixels in order, and say which ones repeat when a script changes the page
  • Can find and fix common accessibility gaps: unnamed controls, unhelpful alt text and controls the keyboard can't reach
  • Can measure what makes a page slow and pick the change that saves the most download time
Module 5 · 1h
Make it interactive Locked
What you'll be able to do
  • Can link a script with defer and prove it runs by checking the console
  • Can run code on taps, typing and form sends with the right event listener, and stop a form from reloading
  • Can find elements with querySelector and change their text and classes in the live DOM
  • Can load JSON with fetch, update part of the page, and handle both a failed network and an error status
Module 6 · 36m
Ship it Locked
What you'll be able to do
  • Can use the Elements and Network panels in DevTools to find why a page looks or loads wrong
  • Can decide whether a site needs a static host or a server, and explain why file:// isn't live
  • Can explain what a domain and HTTPS each add, and why a bought domain needs a DNS record
  • Can write a unique page title and avoid keyword-stuffing tricks that backfire

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