A circuit tester is a handheld electrical testing device used to check the presence of voltage, continuity, and basic electrical faults in circuits, outlets, switches, and wiring systems. It helps technicians and electricians quickly identify live wires, open circuits, and connection issues during installation, maintenance, and troubleshooting tasks. Designed for ease of use, most circuit testers feature a durable body, clear indicators, and reliable performance in residential, commercial, and industrial environments. Its compact size makes it convenient to carry and use in tight working spaces, improving safety and efficiency when working with electrical systems.