Device drivers are sets of instructions that allow the operating system to communicate with a specific type of hardware device. They provide a standardized interface between the operating system and the hardware device.
When a peripheral device is connected to a computer, the operating system will typically load the appropriate device driver for the device. This device driver will then allow the operating system to communicate with the device.
For example, when you connect a printer to a computer, the operating system will load the printer's device driver. This device driver will then allow the operating system to send print jobs to the printer.