Edited sentence: A hard disk platter (or disk) is a component of a hard disk drive: it is the circular disk on which the magnetic data are stored.A platter can store information on both sides, requiring two heads per platter.Hard drives typically have several platters which are mounted on the same spindle.The rigid nature of the platters in a hard drive is what gives them their name (as opposed to the flexible materials which are used to make floppy disks)