MDN Web Docs
The reference for HTML, CSS, JavaScript and the browser APIs, with accurate compatibility data on every page. When an answer from a tutorial and an answer from MDN disagree, MDN is right.
Guide
Web Development
Mozilla
Ongoing reference
All
Free
What it is
The documentation for the web platform itself, maintained by Mozilla with contributions from the other browser vendors, covering every element, property, method and API with examples and browser support tables.
Why it should be your default
Search results for web questions are dominated by tutorials of unknown age, and the web platform changes. MDN pages carry the actual specification behaviour and a compatibility table generated from real browser data, which means you learn what is true rather than what was true in 2019.
How to use it well
Search with mdn appended to your query, or install the site as a search shortcut. The learning area is also a genuinely good structured introduction for beginners, which many people never notice because they only ever arrive at reference pages.
Best for: every web developer, at every level, permanently.
Ready to start?
Opens on Mozilla in a new tab.
Stuck on something specific?
Writing only gets you so far. If you want an answer to your situation rather than the general case, book a session and we will work through it together. Every session is free; a few slots open each week.
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