trackpads
A trackpad, or touchpad, is a flat input device that detects finger position and movement on its surface. It is widely used as the primary pointing device on laptops and is available as external devices for desktops.
Most modern trackpads use capacitive sensing: a grid of electrodes beneath the surface detects changes in capacitance
Clicking is usually done by tapping, pressing in a designated area, or by a separate physical button
Gestures are a major feature: two-finger scrolling, pinch-to-zoom, and three- or four-finger swipes for switching apps
Form factors range from compact external pads to large laptop pads. Some manufacturers use buttonless designs