computer hardware
input/output, processing, comunication, storage devices
input/output devices
An input device ...
is a device that can be used to insert data into a computer or other computational device. An example for this is a USB stick. This is used to store data and an advantage of this is the storage capacity is more yet, a disadvantage is that it can be lost very easily. Also another input device is a standard computer mouse. The mouse is used to move a point and click the device using a laser light to select items on the screen.
Output devices...
are devices which are used to display the data to the user either in the form of hard copy or soft copy. For example, speakers receive the sound in the form of electric current from the sound card and convert it to sound format. The most common output device is the monitor or VDU.
Storage devices...
Storage devices are the data storage devices that are used in the computers to store the data. Some of them can be classified as the removable data storage devices and the others as non removable data storage devices. The memory is of two types; one is the primary memory and the other one is the secondary memory. The primary Memory is the volatile memory and the other is non volatile memory. The volatile memory is known to be erasable and the non volatile memory is the one where in the contents cannot be erased. In this case, when we talk about data storage devices it is generally assumed to be secondary memory.