The computer mouse was named after its resemblance to a real mouse, with the cord acting as a tail and the held part as the body. Douglas Engelbart invented the first computer mouse in 1968, which was a small wooden block with wheels and a long cable. Early mice tracked movement using external wheels or a rolling ball inside, while modern optical and laser mice use light sensors to detect movement relative to surfaces. Other mouse types include inertial mice that track movement without a surface using accelerometers, and 3D mice that provide multiple degrees of freedom through ultrasound.