Fitts's Law

Fitts's law is a predictive model of human movement that describes the time required to rapidly move to a target area as a function of the distance to the target and the target's size. Widely used in human-computer interaction (HCI) since the 1970s, it quantifies pointing efficiency through a metric called throughput (bits per second), which combines speed and accuracy. Fitts's law is commonly used to evaluate and compare input devices and interaction techniques, including assistive technologies for people with motor impairments, though research has shown it may be less reliable for people with limited fine motor function.