Though the computer you are now using is a modern development, computers have actually been around for a long time.
The abacus, a simple, hand-operated calculator, is one of the earliest computers. The Greek historian Herodotus (c450 BC) mentioned that the Egyptians had a form of abacus. The abacus is still widely used in China and other parts of East Asia.
In 1834 British mathematician Charles Babbage designed a mechanical calculator, and later electronic computers were made possible by the vacuum tube. But vacuum tubes are large, so the computers of the 1940s were as big as a house.
With the invention of transistors and integrated circuits, the calculating part of the computer was reduced to a chip about an inch square, so computers can now fit on a desk, or even a lap.
Though you see much more, computers really only use two numbers, zero and one. By combining zero and one in different ways, modern computers can express not only numbers, but also letters and symbols. This enables them to do mathematical calculations, writing, art work, planning, education, games and other tasks.
