A Continuity Tester is a simple electrical device used to check if there is a complete path for current to flow in a circuit. It typically consists of a battery, a light bulb or LED, and two probes. When the probes touch two points in a circuit, the tester lights up if there is continuity, indicating that the circuit is complete. These testers are commonly used in various applications, such as troubleshooting electrical systems in vehicles or checking connections in household wiring. They help ensure that components like fuses, switches, and wires are functioning properly and safely.