A computer is a machine for manipulating data according to a list of instructions.

Computers have many physical forms. Early electronic computers were the size of a large room, engrossing as much power as several hundred modern personal computers. Today, computers can be made small enough to fit into a wrist watch and be powered from a watch battery. The society has come to recognize personal computers and their portable equivalents (the laptop computers) as icons of the information age; they are what most people think of as "a computer". However, the most common form of a computer in use today is by far the embedded computer. They may be found in machines ranging from a fighter aircraft to industrial robots, digital cameras, and even children's toys.