The hard disk is the most important storage device for the computer. Hard disks consist of one or more discs made of aluminum or glass. These discs are covered with ferromagnetic materials.
Most hard drives are fixed hard drives and are permanently sealed in hard drives. The early hard disk storage medium is replaceable, but today's typical hard disk is a fixed storage medium and is blocked in the hard disk. With the development, mobile hard disks have also appeared, and are becoming more and more popular and more and more kinds. Most of the hard disks installed on the microcomputer are called Winchester hard disk, or "temperature disk" for short. The so-called Winchester disk is actually a technology developed by IBM's Research Institute in Winchester street in Campbell, California, United States. It was first applied to IBM3340 hard disk storage in 1973, so this technology is called Winchester technology.