Richard Feynman Explains Hardware, Software and Heuristics

Frequently recommended as the clearest plain-language explanation of what a computer fundamentally is, with at least one commenter saying it changed how they think about programming.

A lecture by Richard Feynman on how computers work, using the analogy of a filing clerk that becomes progressively dumber and faster. It also covers heuristics and how computers handle data and solve problems in finite time.