Screen

A computer, smartphone, TV and other device's screen can be regroup under the term of flat-panel display (FPD).

LCD

Liquid-crystal displays (LCD) screens don't emit light by itself. It just includes a layer made up of several blocks that are filled with liquid crystals. By changing the electrical current in each block, the liquid crystals turn clear or solid, letting light pass through it or not.

Some device can even use different "triggers", such as pressure, to change liquid crystal state.