An electric circuit through which electricity flows and the load can perform its function is called closed circuit.
An electric circuit through which the current does not flow and load cannot work is called an open circuit.
[caption id="attachment_13021" align="aligncenter" width="300"] open and closed electric circuits[/caption]Closed circuit means a complete electrical connection around which current flows or circulates. When you have a series of electrical wires connecting to each other and completing a circuit so that current travels from one end of the circle to the other.An open circuit is one where the continuity has been broken by an interruption in the path for current to flow. A closed circuit is one that is complete, with good continuity throughout. A device designed to open or close a circuit under controlled conditions is called a switch.
A circuit is considered to be closed when electricity flows from an energy source to the desired endpoint (and back to the source) of the circuit. In other words, a closed circuit has a complete path for current to flow, whereas an open circuit doesn't, which means that it's not functional.