Electricity is carried through metallic wires, called conductors.In the process, electrons move through metallic conductorsthat offer resistance (the value depends on the particularmetal used), to the passage of electrons. This leads to the productionof heat and loss of energy. This heating process isutilised in many electrical devices. However, for transmissionof electrical energy from the power plants to the user and inmany other applications, it would be a great boon if no energywas lost to resistance. The discovery of superconductivity byHeike Kamerlingh Onnes in 1911 at Leiden, offered a glimmerof hope to make this dream possible. It was a discoverytotally unexpected at that time, and we owe this discovery tothe painstaking andmethodical investigations of Onnes – firstto produce very low temperatures, and then measure propertiesof materials at these freezing temperatures.