Notes longer than the article
Ada translated from French an article about Charles Babbage's Analytical Engine and added her own notes to it, about three times longer than the original text. In the final note, Note G, she described step by step how to compute Bernoulli numbers.
A vision of the computer
Babbage saw the machine mainly as a calculator. Ada wrote that if notes and harmony could be expressed as symbols, the machine could compose music. In doing so she foresaw computers that process text, images and sound.
Legacy
The machine was never built in her lifetime, so the program never ran. Even so, Ada is a symbol of programming. The US Department of Defense named the programming language Ada after her, and the second Tuesday of October is Ada Lovelace Day, honouring women in science and technology.