What is a test lamp and its uses?

a test lamp i literrally a bulb connected to two wires. it was used to check if you had any current or voltage in a circuit. you would just take the build with the two wires and touch it with the curcuit. if the bulb lights up means that you have a complete circuit if not it means that the curcuit is working. The test lamp is like a medival tool to a multimeter