Mouse is a hand held device that lets you point to and selected items on your screen. In a PC mouse there are mostly 2-3 buttons and on a Mac there is one. A ball under the mouse senses movement. To ensure smooth motion your should remove the ball and clean it regularly.
Scanner - Scanners allow a pc to convert a picture or object into digital code that allows the computer to display and use an image.
Modem - The piece of equipment that allows a computer to communicate with other computers over telephone lines is called a modem.
Pen- The pen lets you draw on what is called a digitizing tablet that mirrors the surface area of the computer screen.