The first computer programmer was arguably Ada Lovelace, who in the 1840s wrote an algorithm for a mechanical computer that was never actually built.

Working from Charles Babbage's designs for his Analytical Engine, Lovelace wrote notes describing how it could compute a sequence of numbers — and, remarkably, mused that such a machine might one day handle more than pure arithmetic, like composing music. The machine was never completed in her lifetime, making her a programmer for hardware that didn't yet exist.