Computer

A computer is a machine for manipulating data according to a list of instructions. Computers take plentiful physical forms. Early electronic computers were the size of a large room, overriding 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. Society has come to distinguish personal computers and their portable equivalent, the laptop computer, as icons of the information age; they are what most people think of as a computer. However, the most general form of computer in use today is by far the embedded computer. Embedded computers are small, simple devices that are often used to organize other devices—for example; they may be found in machines ranging from fighter aircraft to industrial robots, digital cameras, and even children's toys.
The ability to store and implement programs makes computers extremely versatile and distinguishes them from calculators. The Church–Turing thesis is a mathematical statement of this flexibility: Any computer with a certain minimum capability is, in principle, capable of performing the same tasks that any other computer can perform. Therefore, computers with capability and complexity ranging from that of a personal digital assistant to a supercomputer are all able to perform the same computational tasks as long as time and storage capability are not considerations.