Professional Answer: The primary purpose of earthing (also known as grounding) is to ensure safety for both people and equipment. By connecting the non-current-carrying metallic parts of an electrical system to the earth, we provide a safe, low-resistance path for fault currents to flow directly to the ground. This prevents dangerous voltages from building up on the equipment's chassis, which could cause electric shock, equipment damage, or electrical fires in the event of a fault. Earthing also helps stabilize system voltage and protects against lightning strikes and power surges.