What is the term for devices that connect to a computer system to add functionality?

The correct choice is a peripheral device, which specifically refers to external hardware that connects to a computer system to enhance its capabilities or functionality. Peripheral devices can take various forms, including printers, scanners, mice, keyboards, and external drives, allowing users to interact with the computer or expand its features beyond the primary components.

Hardware overall encompasses all the physical components of a computer system, including both internal and external devices, but does not specifically refer to those that provide additional functions. Software denotes programs and applications that run on hardware to perform tasks, while firmware refers to specific programming that is embedded within a hardware device, providing low-level control for the device's specific functions. Understanding these distinctions clarifies why the term "peripheral device" most accurately describes devices that connect to a computer to add functionality.