A hard disk, also referred to as a disk drive or hard drive, is a magnetic disk for storing computer data. It uses magnetic storage to store and retrieve digital data using one or more rigid, rapidly rotating platters coated with magnetic material. The platters are paired with magnetic heads that read and write data to the platter surfaces. Data is randomly accessed, meaning individual blocks of data can be retrieved and stored in any order. Hard disks contrast with floppy disks, as they are faster and hold more data than floppy disks.
Hard disks were introduced by IBM in 1956 and were the dominant secondary storage devices for general purpose computers in the early 1960s. Today, computers typically come with a hard disk that contains anywhere from billions to trillions of bytes of storage. The rotation speed of a hard disk in these computers can vary anywhere between 5,400 rotations per minute (rpm) and 7,200 rpm. Hard disks with higher rpm are normally found in high-end workstations and enterprises.
Hard disks vs. solid state drives (SSD)
Solid state drives (SSDs) have led to a decline in hard disk use and popularity. An SSD is a high-performance, plug-and-play storage device that requires no moving parts. It is faster, more durable, and uses less power than a hard disk. A major drawback of the SSD is it’s more expensive in terms of dollar per gigabyte.
An SSD fits into the same external and internal drive bay of a hard disk. While hard disks still exist in cheaper and older systems, SSDs are now used in most mainstream systems, such as the MacBook Pro. They are much faster and will boot in less than a minute. A hard disk takes time to speed up, and will almost always boot slower, launch slower, and transfer files slower. Hard disks provide much more space for the price, so it’s better for those needing high capacity.