Frontend development

Stage 1 · Lesson 2 of 9

HTTP methods, status codes and headers

How the web works, HTML and CSS

Every exchange between browser and server is an request followed by a response. The says what the request wants: GET reads, POST creates or submits, PUT and PATCH update, DELETE removes. The in the response says what happened.

A 2xx code (200 to 299) means it worked, and 3xx means a to somewhere else. A 4xx code means the client asked for something wrong: 404 not found, 401 not signed in, 403 not allowed. A 5xx code means the server itself failed.

Headers carry the rest, such as the content type, caching rules and cookies. You will read all of this in the Network tab for the rest of your career. It also decides, later on, how you handle fetch errors and caching.

Common trapassuming a response arrived means it succeeded: a 500 is still a response.

A question to check yourself, an AI practice session and 2 cheat sheet entries come with the full roadmap. Unlock

Resources for this stage

Start with· follow one of these

  • CourseFree
    The Odin Project

    The Odin Project · Beginner

    Foundations course: HTML, CSS and the web built in your own editor, not a sandbox

  • GuideFree
    web.dev

    Google · Intermediate

    Free Learn HTML, Learn CSS and Learn Accessibility courses explain the why behind layout

Practise

  • Real designs to rebuild, which is where CSS layout finally sticks

Keep handy

  • The reference for every HTML element and CSS property, with browser support notes

  • Quick syntax lookups and try it editors when you only need a reminder

Also worth your time

Mark this stage as not done?