Device drivers serve as the intermediary between the operating system and the hardware connected to a computer, such as a printer, graphics card, or network adapter. They enable the OS to send commands to hardware devices, receive feedback, and facilitate the user's interaction with various peripherals. Drivers are specific to the operating system and hardware, meaning that a device may require different drivers depending on the environment in which it operates. Without the appropriate drivers, the OS may not successfully control the hardware, leading to a non-functional device or degraded performance.