A computer is a machine that can be programmed to carry out sequences o arithmetic or logical operations automatically. Modern computers can perform a wide range of tasks. A computer system is a "complete" computer that includes the hardware, operating system and peripheral equipment needed and used for "full" operation. This term may also refer to a group of computers that are lined and function together, such as a computer network or computer cluster. 

A broad range of industrial and consumer products use computers as control systems. Simple special purpose devices like microwave ovens and remotes controls are included, as are factory devices like industrial robots and computer- aided design, as well as general- purpose devices like personal computers and mobile device like smartphones. Computers power the internet, which links hundreds of millions of other computers and users. 

Early computers were meant to be used only for calculations. Simple manual instruments like the abacus have aided people in doing calculations since ancient times. Early in the industrial Revolution, some mechanical device were built to automate long tedious tasks, such as guiding pasterns for looms. first digital electronic machines did specialized analog calculations in the early 20th century. The first digital electronic calculating machines were developed during world war II.


Conventionally, a modern computer consists of at least one processing element, typically a central processing unit (CPU) in the form of a microprocessor, along with some types of computer memory, typically semiconductor memory chips. The processing element carries out arithmetic and logical operations and a sequencing and control unit can change the order of operations in response to stored information. Peripheral device include input devices (Keyboards, mouse, joystick, etc) , output devices (monitor screens, printers, etc.) and input/output devices that perform both functions . Peripheral devices allow information to be retrieved from an external source and they enable the result of operations to be save and retrieved .