Unlike solid state drives (SSD), hard disk drives (HDD) have several mechanical parts that move together to store and retrieve data.
Inside an HDD device, there are spinning platters with magnetic coatings. Each platter has tracks or concentric circles on it called segments. Each track and sector number creates a unique address that the HDD technology uses to organize and locate data.
A motor spins an internal actuator arm with a read/write head. By reading the charge information on particular segments, the read/write head records and retrieves information. An I/O controller and the operating system of the HDD tell the mechanical parts what to do and when.