The function of a hard drive in a computer is to provide long-term storage for data and applications. It uses magnetic storage technology to read and write digital information. Hard drives are critical for storing the operating system, software programs, and user files such as documents, photos, and videos. They offer substantial storage capacity and allow for data retrieval when the computer is powered on. While traditional hard drives (HDDs) are being complemented by faster options like solid-state drives (SSDs), they remain a common choice for bulk storage needs in computing.