Hard drive is a device that stores information in virtually all desktop and laptop computers. Most drives include one or more rigid magnetic disks that hold the data. These disks are called hard disks or platters. Many people use the term hard disk to refer to the entire hard drive. The platters are usually fixed inside the drive and cannot be removed. They are stacked on top of one another. Data are stored on each side of a platter’s surface, on circular bands called tracks. A hard drive has thousands of tracks. Each side of a platter has a device called a read/write head that moves in and out to specific tracks of the spinning platter to store or to call up data for the computer to use. Hard drives are also known as fixed-disk drives.
Hard drives have much more storage capacity than removable disks. Hard drives can also call up data faster than CD-ROM’s (Compact Disc Read-Only Memory units). The time needed to find a piece of data on a hard disk is measured in thousandths of a second. Typical hard disks store gigabytes of data. A gigabyte is about 1 billion bytes. A byte is a single unit of information, such as a letter or a numeral.
