A touchpa (also trackpad) is an input device commonly used in laptop computers. They are used to move the cursor, using motions of the user’s finger. They are a substitute for a computer mouse and are used in place of them when space would make use of a mouse and suitable resting surface inconvenient. Touchpads vary in size but are rarely made larger than 20 square centimeters (about 3 square inches). They can also be found on personal digital assistants (PDAs) and some portable media players.