Keypad

A keypad is a compact input device with a small number of keys, typically arranged in a 3x4 grid (phone keypads) or other constrained layouts. In accessibility contexts, keypads are relevant both as the *only* viable input device for some users — small physical keypads are easier to target for users with tremor or low vision, and can be augmented with tactile features — and as a fundamental constraint in text-entry research, where each key may be assigned multiple characters and disambiguation software (such as T9) is needed to recover the intended word. Keypad-based text-entry research from the cellphone era now informs the design of switch arrays, mini-keyboards for AAC devices, and gaze-typing grids.