a driver is a software able to tell the hadrware what to do.
Hardware without a driver is able to do nothing or almost nothing
every hardware needing a driver has what is called ID Hardware. example VEN_8086&DEV_XXXX
when you install a driver on a OS , if in the file .inf ( a file part of the driver) contains a string that match the Hardware ID, it means the driver is compatible with that hardware and loaded in the OS.