Memristor, the fourth passive component, most simply stated is a state-dependent resistance. Till 2012, we didn’t have any simple memristor to play around with in a lab or in your garage. Now we do… We found that simply touching two metal balls makes a memristor! The device was known as coherer 100 years back and it was used to receive radio signals before the invention of diode. Only an Indian scientist Jagadish Chandra Bose had observed the correct electrical properties for the device qualifying it as a memristor.