The hard drive is where the operating system, software files, and any other installed software is stored. This component of the computer is the main device used for storage of data, and offers the most space than any other component of the computer that stores memory like caches and passwords. Most people's computers designate the hard drive as the "C"drive, especially is using on manufacturer by Microsoft. But the hard disk drive is also referred to as HDD, fixed disk drive, hard drive or fixed drive.