Keyboard is a standard input device which is used to feed data into the computer and to control its operation. A keyboard can either be internal or external. Internal keyboards are for notebooks only, while External keyboards can be used with notebooks, desktops, and servers. External keyboards are available with either PS2 or USB interface connections. The number of keys in a keyboard determines the total characters and operations that can be carried out. The interface type determines the compatibility of the keyboard with your system.