One of the features of Operating System is it manages and communicates with your system hardware by means of Drivers.
Drivers are special software within the OS that interacts to the hardware. Drivers uses kernel, a part of the operating system that functions intended to it. For example, when you press Ctrl and P keys on the keyboard, the kernel would recognize this command and would trigger the corresponding hardware in relation to this command. In this case, the corresponding hardware is printer. The kernel would tell the printer to print the document.