What is a Driver in the context of computer systems?

A driver is a specialized program that serves as an intermediary between the operating system (OS) and the hardware devices in a computer system. Its primary function is to allow the OS to communicate with hardware components, such as printers, graphics cards, or storage devices, by translating commands from the OS into a language that the hardware can understand. This is crucial since different hardware components have varying protocols and requirements for operation. Without the appropriate driver, the OS would not be able to utilize the hardware effectively, leading to potential issues with functionality.

In contrast, the other options do not accurately represent the role of a driver. A graphical interface for users is more related to user experience and interaction rather than hardware communication. A file format for system updates refers to the method by which updates are packaged and distributed, not the mechanism behind hardware functionality. Similarly, a security feature to manage access pertains to permissions and controls over the system rather than the communication between the OS and hardware devices. Therefore, identifying a driver as a program that enables communication between the OS and hardware captures its essential purpose within computer systems.