Dicuss The Imporatnce Of Earthing Of Appliances?

An  interesting question. All appliances need at least two wires (the live and the neutral) to form a complete circuit from the supply, through the appliance, and back to the supply.
The live (L) wire (brown) delivers the energy at the high alternating voltage to the appliance. The neutral (N) wire (blue) completes the circuit by forming a path for the current back to the supply. It is usually at zero volts.

The earth (E) wire (green with yellow) is a low resistance wire, usually connected to the metal casing of the appliance. Earthing protects any user of the appliance from an electric shock. If the metal casing should accidentally become live (e.g. when the live wire is not properly screwed on and touches the metal casing of the appliance). The large current that flows from the loose live wire through the metal casing and the earth wire (a low resistance wire) will blow the circuit fuse and cut off the supply to the appliance.

It should be remembered that current will always flow through a path which offers minimum resistance. In this case the earth wire being a low resistance wire provides an alternative path for the current to flow, should the metal casing accidentally become live.