An erasable optical disk is the one which can be erased and then loaded with new data content all over again. These generally come with a RW label. These are based on a technology popularly known as Magnetic Optical which involves the application of heat on a precise point on the disk surface and magnetizing it using a laser. Magnetizing alters the polarity of the point indicating data value ‘1’. Erasing too is achieved by heating it with a high energy laser to a certain critical level where the crystal polarity is reset to all 0’s.