The difference engine was the first machine that is now considered as a computer. The British mathematician Charles Babbage conceived the difference engine in 1822. The difference engine was only partially built when Babbage conceived the idea of another, more sophisticated machine called an Analytical Engine. One of Babbage's co-workers was Ada Lovelace, for whom the Ada programming language was subsequently named.

Babbage intended his difference engine to automatically calculate mathematical tables, such as logarithmic and trigonometric functions, particularly as they applied to navigation tables. Accurate navigation data was of great interest to the British in Babbage's day, for use by their sea-going merchant and naval vessels. The machine was intended to be steam-powered and fully automatic, even to the point of printing out the resulting tables. It was also to be controlled by a fixed instruction program, somewhat analogous to the modern day computer operating system...