(1) A dust, dirt and waterproof keyboard constructed of two thin plastic sheets (membranes) that contain flexible printed circuits made of electrically conductive ink. The top membrane is the printed keyboard and a spacer sheet with holes is in the middle. When a user presses a simulated key, the top membrane is pushed through the spacer hole and makes contact with the bottom membrane, completing the circuit. Membrane keyboards, which are much hardier than normal key switch keyboards, offer the advantage of complete customization by programming the cell matrix for any application.

(2) Most computer keyboards today use the technology in definition #1 above, but with molded key caps rather than printed keys. As a result, they are not as hazard proof, but the economical membrane construction enables the keyboard to retail at lower cost. Contrast with mechanical keyboard.