The hard disk drive (HDD) is a secondary storage type. As such, it is a computer component that uses the motor to spin the disc, has a magnetic read-and-write head, and has metal platters that permanently store data. Each platter contains tracks and sectors. The starting point for storing data in HDDs is the outer track. In the case of an HDD with one disc platter, the read-and-write head is located above the platter at a distance of microns, thus never touching the disc. If it does, then physical damage occurs. The data storage capacity is measured in bytes (nowadays it is GB), while the disc spinning speed is measured in rotations per minute (RPM). Most common RPM rates for PCs and laptops are from 5400 RPM to 7200 RPM, while for servers the most common RPM rates are from 10,000 RPM to 15,000 RPM. Usually, the HDD is located inside the computer's case and is mounted in drive bays. However, there are also external HDDs, mainly used for installing the operating system and applications, as well as for storing data. In the event of HDD disposal, it is recommended to perform disk shredding.