Nature of Code
natureofcode.com
Daniel Shiffman's free online book and companion videos teaching creative coding through simulations of natural systems — physics, agents, neural networks, and evolution.
Why it is useful
Makes complex algorithmic concepts tangible by implementing them as visual, interactive simulations — you understand particle physics and genetic algorithms by building them, not by reading equations. The coding approach (p5.js) is accessible enough for beginners while the mathematical depth is substantial. The companion Coding Train YouTube videos make the written content even more approachable.