A mouse is a small object that runs across a ﬂat surface and has at least one, but typically two or three, buttons that send electronic signals to the GUI. Its name is derived from its appearance—a small rounded rectangle shape with a single cord attached at one end. Mice can be:
- Mechanical—A ball on the underside runs along a ﬂat surface. Mechanical rollers detect the direction the ball is rolling and move the screen pointer accordingly.
- Optical—A laser detects the mouse’s movement. Optical mice have no mechanical moving parts, and they respond more quickly and precisely than other types of mice.
A trackball is basically an upside down mouse. The ball is mounted on the top of the case instead of the bottom and signals are sent to the computer by moving the ball with your thumb, ﬁngers, or palm instead of by rolling the ball across a ﬂat surface. Like a mouse, a trackball has at least one button that is used to send electronic signals to the computer.
Touch Pad :
A touch pad is a small, touch-sensitive pad where you run your ﬁnger across the surface to send electronic signals to the computer to control the pointer on the screen. Touch pads can have buttons like a mouse or trackball, or the touch pad can be conﬁgured to detect ﬁnger taps on its surface and process those signals like button clicks.
A trackpoint, or pointing stick, is most commonly found on laptops. Located in the center of the key- board, the trackpoint is a small joystick-like button that responds to user force in all directions in order to move the mouse pointer on screen.
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