The device used to stop and start the flow of electricity in a circuit is a switch.

Here's why:

* Switch: A switch acts like a gate. When it's closed, it allows electricity to flow through the circuit. When it's open, it breaks the circuit and stops the flow of electricity.

There are many different types of switches, each with their own uses, such as:

* Toggle Switches: Commonly found in household appliances and light fixtures.

* Pushbutton Switches: Used for temporary activation (like a doorbell).

* Rotary Switches: Used to select from multiple options (like a volume knob).

* Circuit Breakers: A type of switch that automatically breaks the circuit if there's an overload or short circuit.

Let me know if you'd like to learn more about any specific type of switch!