A hard disk is a metal plate with magnetic surfaces, and it is a component of a hard disk drive. The hard drive equipment reads from and writes to the surface of the disk. This type of drive is common in most personal computers, as well as other large devices that include data storage.
In a hard drive, an actuator arm assembly locates platter cylinders so that it can read from and write to the disk. Read and write heads act as the agents for these functions. The total assembly fits into a rectangular metal container. In traditional computing, the hard disk was the internal structure for storing data in a workstation or personal computer. External disks were called “floppy disks” because they had soft internal media. The emergence of new types of drives has made floppy disk technology largely obsolete.
Today, a hard disk can be either part of an internal disk drive, or an external drive that connects to a computer. Internal and external drives provide a common method for storing a lot of executable programs. They also provide a stable way to hold many gigabytes of data in a separate drive that can be disconnected from a laptop or desktop computer. An innovation called Perpendicular Magnetic Recording (PMR) is increasing the amount of data that a hard drive can hold.
Hard drives are getting competition from other new technologies, including the flash drive. A flash drive is a solid state drive, where a new form of data storage replaces the circular hard disk technology. The hard drive and the solid state drive often share the same USB connections to the computer, but the way data is recorded and stored is different.
Periodically, a hard drive needs to be defragmented, where the computer re-organizes all of what is written on the drive surface for optimized performance. Because a solid state drive doesn’t write to a disk, it does not need to be defragmented. Solid state drives can be more expensive than hard drives, but they are becoming a more common way to hold and deliver data. Many manufacturers are using solid state drive technology for smaller electronic devices as well as ruggedized computers and some netbooks.