When wires connected together end to end, it forms a closed loop. Through this closed loop electrons flow in a continuous way as illustrated in Fig. Electric Circuit.
Electrons flow is nothing but an electric current. Hence, for an electric current to flow there must be a closed path or loop. If there is a break in the path then electrons will not be able to complete the path around it. If electrons are not able to flow then there will not be any current in the circuit. To force electron to flow in a direction source of energy needed. Such source is usually a battery. Hence, an electron flow originates from a battery source circulates the path and terminates at source again. An electric circuit consists of various electric components ( battery, switches, bulb, resistors,….) connected together in a closed loop.
Definition : Electric Circuit is any closed path through which an electric current or electrons flow.