What electrical component is used to protect other circuit components from current overloads?

The fuse is the component specifically designed to protect circuit components from current overloads. It functions by interrupting the flow of electricity when the current exceeds a predetermined level, thereby preventing damage to other components in the circuit. When the current flowing through the fuse becomes too high due to an overload or short circuit, the fuse element heats up and melts, breaking the circuit and stopping the flow of electricity. This simple yet effective safety mechanism helps to ensure the longevity of sensitive electronic components.

In contrast, a thyratron is a type of gas-filled tube used as a switch or amplifier in high-power applications, while a varactor is a diode that varies its capacitance based on the voltage applied across it, primarily used in tuning circuits. These components serve different functions and are not primarily intended for overload protection, which makes them unsuitable answers for this question. The choice that stands out for protecting circuits is clearly the fuse.