A Hard Disk Drive (HDD) is a data storage device that uses magnetic storage to store and retrieve digital information. HDDs consist of spinning disks, or platters, coated with magnetic material and a read/write head that accesses data as the platters spin. HDDs have been the primary storage device in computers for decades, offering large storage capacities at relatively low costs. While slower and less durable than solid-state drives (SSDs), HDDs remain a common choice for mass storage in desktop computers, external drives, and servers. They are typically used to store files, applications, and operating systems.