Long form explainers that start with a question most people get wrong, then work through the physics until it makes sense.

Veritasium - Physics and Engineering, Explained

Linear algebra, calculus and neural networks taught through animation, aimed at building intuition before notation.

3Blue1Brown - Mathematics, Visually

Complete recorded lecture series in computer science, physics and mathematics, matched to the published course notes.

Working mathematicians talking through problems, proofs and oddities on brown paper, one idea per video.

Compressed walkthroughs of frameworks, languages and developer tooling, usually in about a hundred seconds.

The official interactive guide to components, state, effects and hooks, written by the team that maintains the library.

Course style guides on performance, accessibility, responsive layout and modern browser APIs, written by Chrome engineers.

Introductory material on the event loop, modules, streams and file access for running JavaScript outside the browser.

Routing, rendering, data fetching and deployment guides for the React framework, with side by side app and pages examples.

Millions of answered programming questions, ranked by community votes, covering every mainstream language and framework.

Millions of collaboratively written articles in more than three hundred languages, covering history, science, culture and biography.

Lecture notes, problem sets and exams from thousands of real MIT courses, published openly with no registration.

Video lessons and exercises from arithmetic through calculus, plus science, economics and test preparation, free to use.