A membrane keyboard is a computer keyboard whose “keys” are not separate, moving parts, as with the majority of other keyboards,but rather are pressure pads that have only outlines and symbols printed on a flat, flexible surface. Very little, if any ,tactile feedback is felt when using such a keyboard and error-free blind typing is difficult.
Membrane keyboards work with electrical contact between the keyboard surface and the underlying circuits when key-top areas are pressed.
For the Modern PC keyboards, they re essentially a membrane keyboard mechanism covered with an array of dome switches which give positive tactile feedback.