The symbol for the diode that is being used when you draw electrical diagrams shows its rectifying property. The symbol is an arrow that shows in which direction the current is allowed to pass, i.e. the forward biased direction of the diode. Today the diode is still being used as a detector in electrical circuits such as in the television or radio receiver. The diode is also being used as a converter of AC (Alternating Current) to DC (Direct Current) in power supply units.