How will you use the conduction tester to find if an object is a conductor or insulator of electricity?

Conduction tester - It is a simple device used to test whether a given object is a conductor or an insulator.

We know that current only flows through those objects which are good conductors of electricity. 

So, to test whether a given object is a conductor or an insulator, the two ends of a conduction tester are touched with an object, if the object is a good conductor of electricity then the current will flow through the tester and the bulb will glow, whereas, if the object is an insulator (or, a bad conductor of the electricity) then the current will not flow through the tester and the bulb will not glow.