The function of a hard disk drive in a computer is to store and retrieve digital data. It utilizes magnetic storage to retain information on rotating disks, allowing for access to large volumes of data. Hard disk drives are essential for operating systems, applications, and personal files, providing the necessary space for storage. While they offer higher capacities compared to traditional storage options, their mechanical components make them slower than solid-state drives (SSDs). Despite this, HDDs remain popular due to their cost-effectiveness and vast storage capabilities.