Left buttonThe main button, pressed with the index finger to click and select.
Right buttonThe second button, often used to open a menu of options.
Scroll wheelThe wheel between the buttons that scrolls the page. It also works as a button when pressed down.
BodyShaped for the hand to rest on as it moves.
CableThe cable that connects the mouse to the computer. Cordless mice use radio, such as Bluetooth or a small USB receiver, instead.
USB plugGoes into the computer's USB port. The plug on the end of the cable.
Underneath: 3 3
SensorThe optical sensor, a tiny low-resolution camera. It takes pictures of the surface to track how the mouse moves.
LEDLights the surface so the sensor can see it. It is a light-emitting diode. Laser mice use a laser instead.
FeetSmall smooth pads on the underside. They help the mouse glide across the desk. Also called mouse skates.
How this list was compiled: Read 2026-09-27. (1) Wikipedia, Computer mouse, https://en.wikipedia.org/wiki/Computer_mouse : a wired mouse with left and right buttons, a scroll wheel that is also a button when pressed, and a cable that plugs into the computer; many modern mice are cordless, using Bluetooth, Wi-Fi or a receiver plugged into a USB port; small pads on the bottom, called mouse feet or skates, help it slide; most modern mice use optical movement detection. (2) Wikipedia, Optical mouse, https://en.wikipedia.org/wiki/Optical_mouse : a light source, typically an LED, and a light detector; the sensor is essentially a tiny low-resolution video camera taking successive images of the surface; laser mice use a laser. Licence: own work
The drawing: Drawn for this site by script, 2026-09-27. Own work, nothing traced. Licence: own work
How it works
These are the parts of a computer mouse on a wired optical mouse, drawn from above and then turned over. Start with the 6 main parts, then underneath.
Read the full guide
On top
The left button is the main one; the right button often opens a menu. The scroll wheel between them scrolls the page and clicks as a third button. The cable ends in a USB plug.
Underneath
An LED lights the desk, and the optical sensor, a tiny camera, takes pictures of it to track how the mouse moves. Smooth feet help it glide.
A cordless mouse has no cable: it talks to the computer by Bluetooth or through a small receiver plugged into a USB port.
Questions and answers
What are the main parts of a computer mouse?
The left and right buttons, the scroll wheel between them, the body your hand rests on, and a cable or wireless link. Underneath is the sensor that tracks movement.
How does an optical mouse work?
An LED lights the surface under it, and a tiny camera-like sensor takes pictures of that surface many times a second. Comparing them shows how the mouse has moved.
What are the pads under a mouse called?
Mouse feet, or mouse skates: small smooth pads that help the mouse slide across the desk or mat.