The idea of the computer first occurred to the British inventor Charles Babbage (picture, left) in about 1833. Others had made calculating machines before him. But Babbage was the first person to conceive of a machine that could be programmed to carry out different calculating operations, as a computer can. Babbage designed a machine called the Analytical Engine that had the basic feature of a modern computer. It was to be a mechanical computer, containing complex systems of shafts and gear wheels. However, only some parts of the Analytical Engine (see photo below) could be built. The engineering required to complete it was far beyond the techniques of the age, and Babbage died in 1871 without knowing whether his computer would work or not.
In fact, Babbage was far ahead of his time. The first computer — a British wartime decoder called Colossus — was not built until 1943. Like modern computers, it used electronics, as mechanical operations were too slow. Colossus and all other computers since are really the descendants of Babbage’s Analytical Engine.