Components of a computer system and modes of use: Types of hardware
Hardware components are often categorised as being either input, output, storage or processing components. Devices which are not an integral part of the CPU are referred to as being peripherals. Peripherals are usually used for either input, storage or output (such as a hard disk, keyboard or printer). A device does not necessarily have to be outside the same physical box as the CPU. The best example of this is the hard disk, which is a peripheral even though it is not usually housed within the main case.
Input devices are hardware devices which take information from the user of the computer system, convert it into electrical signals and transmit it to the processor. The primary function of input devices is to allow humans to interact with the computer system. For instance a mouse allows the user to control the movement of the pointer (a common element in user interface design).
Output devices take data from the computer system and convert it to a form that can be interpreted by humans. For instance a monitor creates a visual electronic display to output information created by the processor to the user.
Storage devices are components which allow data to be stored within a computer system. This includes devices such as hard disk drives and compact disk drives.