Ever wondered how an ATM card stores information? Most of us are aware that the black strip at the back of the card plays an important role in this process. How it works though, isn't as common a knowledge.
The black strip found at the back of most smart cards is essentially a band of magnetic material. Different materials respond differently to a magnetic field. Iron for example, gets ‘magnetized’ in the presence of a magnet, whereas a piece of wood does not.