A diode is an electric component which allows the current to flow in only one direction is called as a diode and the most common type of diode uses a p-n junction.  In other words, a diode is a two-terminal electronic component that conducts electricity or the flow of current in only one direction. A diode has high resistance on one end and low resistance on another end thus restricting the current flow in one direction. Diodes are used in protecting circuits by converting the alternating current (AC) into direct current (DC) and limiting the voltage. Diodes are also called as rectifiers due to they convert the alternating current (AC) into direct current (DC).

As we know a diode is made up of two words that is Di means Two and Ode means electrodes which means that it is a device that has two electrodes – cathode (negative), and anode (positive). It has polarity and is determined by the cathode (negative lead) and anode (negative lead). Most of the diodes allow current to flow if a positive voltage is applied to the anode. When a diode is reverse-biased then it works as an insulator and does not allow current to flow while if a diode is forward-biased then it allows current.

The most common type of diode that uses a p-n junction diode is also called as semiconductor diode due to it conducts in one direction so it is also used for rectification. A diode is made up of a crystal such as Germanium or Silicon so it is also called as crystal diode.