Diode

In electronics, a diode is a type of two-terminal electronic component with a nonlinear – currentvoltage
characteristic. A semiconductor diode, the most common type today, is a crystalline piece of
semiconductor material connected to two electrical terminals. A vacuum tube diode (now rarely used
except in some high-power technologies) is a vacuum tube with two electrodes: a plate and a cathode.
The most common function of a diode is to allow an electric current to pass in one direction (called the
diode's forward direction), while blocking current in the opposite direction (the reverse direction). Thus,
the diode can be thought of as an electronic version of a check valve. This unidirectional behavior is called
rectification, and is used to convert alternating current to direct current, and to extract modulation from radio
signals in radio receivers.