A circuit tester is a simple tool used to check if electrical circuits are functioning properly. It helps identify whether there is power flowing through wires and can detect faults in electrical systems. Circuit testers come in various forms, including multimeters and voltage testers, each designed for specific testing needs. Using a circuit tester is straightforward. The user connects the tester's probes to the circuit or outlet being tested. If the circuit is live, the tester will indicate this through lights or sounds. This tool is essential for electricians and DIY enthusiasts to ensure safety and proper functioning of electrical devices.