Drives
most people are amazed when they discover they can store hundreds of CDs worth of music on an iPod digital music player no bigger than a pack of cards. An iPod (one of the older ones, anyway) is not much more than a hard drive: an incredibly efficient computer device that uses simple magnetism to store vast amounts of information. Hard drives were invented over 50 years ago and have been used in personal computers since the mid-1980s.