A circuit is a closed loop that allows electricity to flow through it. It consists of various components like wires, resistors, and capacitors that work together to control the flow of electric current. When the circuit is complete, electricity can power devices such as light bulbs or motors, making them function. There are two main types of circuits: series and parallel. In a series circuit, all components are connected in a single path, so if one part fails, the entire circuit stops working. In a parallel circuit, components are connected across multiple paths, allowing them to operate independently even if one part fails.