Algorithms
I learn best by watching things move. These are interactive, in-browser visualizers for classic computer science algorithms: press play, scrub through the steps, and watch the source highlight line by line as it runs. Pick a category to dig in.
Watch different algorithms track down a value in an array, and see why keeping it sorted pays off.
Watch a shuffled array settle into order, from bubble sort up to Timsort, one comparison and swap at a time.