What does an HDD primarily serve as in a computer?

An HDD, or hard disk drive, primarily serves as permanent storage for the operating system and applications in a computer. This type of storage is designed to retain data even when the computer is powered off, making it ideal for long-term data storage. Unlike temporary storage, such as RAM, which loses its data when the system is turned off, an HDD enables users to keep their operating system, installed software, files, and documents securely until they choose to delete or overwrite them.

HDDs use magnetic storage technology to write and read data, making them a reliable choice for archiving large amounts of information. Their capacity can range from several hundred gigabytes to multiple terabytes, making them suitable for both personal and enterprise-level computing needs. In contrast, the other choices reflect functions or components that are not the primary role of an HDD.