Who wrote the first algorithm intended for use by a machine?

An English mathematician and writer, chiefly known for her work on Charles Babbage's proposed mechanical general purpose computer (the Analytical Engine), Augusta Ada King-Noel, Countess of Lovelace (Ada Lovelace) was the first person to recognize that Babbage's machine had applications beyond that of pure calculation.

When Ada wrote the world's first machine algorithm, it was for an early computing machine that existed only on paper. She was the person who pointed out that programming languages would primarily be intended for expressing algorithms in a form that could be executed by a mechanical machine or computer.

Much of Ada's work about the mechanical machine was published and overlooked in her time. Although she and Babbage produced hundreds of documents about their work, the potential of the machine, and the use of algorithms, they were mostly ignored. Their key ideas would not emerge again for another hundred years.