What is the purpose of a fuse in an electrical circuit?

A fuse is a critical safety device designed to protect electrical circuits, wiring, and equipment from excessive current flow. It contains a sacrificial piece of wire that is intentionally designed to melt and break the circuit if the current exceeds a specific safe threshold. By breaking the circuit, the fuse removes power during an overload or short circuit. This stops the flow of electricity, preventing wires from overheating, melting their insulation, and causing a fire. While a fuse protects the equipment from overcurrent, it is not designed to prevent electric shocks to people, nor does it filter or smooth power supply ripple. It takes very little current to stop a human heart—far less than the rating of a typical fuse—so it will not blow fast enough to prevent a shock.