An electrical circuit is a closed loop through which electric current can flow. Basic circuits include a power source (like a battery or electrical outlet), conducting wires, a load (device using the electricity, like a light or appliance), and usually a switch to control flow. When the circuit is complete (closed), electricity flows; when broken (open), it stops. Buildings contain many circuits, each protected by a circuit breaker. Understanding circuits helps with basic electrical safety—knowing that turning off a switch breaks the circuit, or that a tripped breaker has interrupted a potentially dangerous overload. Electrical codes specify circuit requirements for safety.