Circuit breaker
The switch in your panel that cuts power to a circuit when it's overloaded.
A circuit breaker is the protective switch inside your service panel that automatically shuts off power to a circuit when it draws too much current — from an overload, a short, or a ground fault. That's what 'tripping' is, and it's the breaker doing its job. You reset one by flipping it fully OFF, then ON. A breaker that trips again and again isn't faulty; it's warning you about an overloaded circuit, a bad device, or a wiring problem that needs an electrician.