is a component that restricts the direction of movement of charge carriers. Essentially, it allows an electric current to flow in one direction, but blocks it in the opposite direction. Thus, the diode can be thought of as an electronic version of a check valve. Circuits that require current in only one direction will typically consist of one or more diodes in the circuit design.
Early diodes included "cat's whisker" crystals and vacuum tube devices (called thermionic valves in British English). Today the most common diodes are made from ultrapure semiconductor materials such as silicon or germanium.
the diode is a rectifier that makes current go into a certain direction and blocks it in the opposite one...it is constructed by a semiconductor PN junction