An electrical circuit is a closed loop that allows electric current to flow. Think of it like water flowing through a pipe - electricity flows through wires in a similar way. For current to flow, there needs to be a power source (like a battery), conductive paths (usually wires), and components called loads that use the electricity (like lights, motors, or sensors). If the loop is broken - for example, by a switch being open - the current can’t flow, and the components won’t work.
Switches are simple devices that either complete or break the circuit. When a switch is “on” (closed), current flows and the connected component gets power. When the switch is “off” (open), the circuit is broken, and the power stops. This makes switches a basic way to control electronic devices.
Transistors are a special type of switch which can turn parts of a circuit on or off based on signals from other parts of the system.
A wiring diagram (also called a circuit or schematic diagram) represents the connections and physical layout of an electrical circuit. It shows how wires are interconnected and where sensors and actuators maybe connected to the system.