A hard disk drive platter or hard disk is the circular magnetic disk on which digital data is stored in a hard disk drive. The rigid nature of the platters is what gives them their name. Hard drives typically have several platters which are mounted on the same spindle. A platter can store information on both sides, typically requiring two recording heads per platter, one per surface.
Hard disk with platter
Inside view of a hard disk
Hard disk drive platter, 2.5" Samsung MP0402H
Destroyed hard disk, glass platter visible
A hard disk drive (HDD), hard disk, hard drive, or fixed disk, is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating platters coated with magnetic material. The platters are paired with magnetic heads, usually arranged on a moving actuator arm, which read and write data to the platter surfaces. Data is accessed in a random-access manner, meaning that individual blocks of data can be stored and retrieved in any order. HDDs are a type of non-volatile storage, retaining stored data when powered off. Modern HDDs are typically in the form of a small rectangular box.
A partially disassembled IBM 350 hard disk drive (RAMAC)
2.5-inch hard disk drive with cover removed
The end of a 3.5 inch hard disk drive with a Serial ATA (SATA) interface
Destroyed hard disk, glass platter visible