The diode is one of the basic non-linear circuit components which conducts the current in only one direction. In operation, it is analogous to a mechanical check valve that allows the flow of fluid in one direction and blocks the flow in another direction. Similarly, diode also allows the flow of electron in only one direction, known as the forward direction. This unidirectional behavior is also known as rectification and is used to convert alternate current(AC) to direct current(DC). It would not be wrong to call this basic element as the flag bearer of the electronic edge. This series contains descriptive as well as application specific articles related to different types of this little yet powerful semiconductor device.