For each host and it's respective host controllers, there is a driver present that provides for the general functionality and operation of the USB system as a whole.
Hardware manufacturers continuously develop drivers for existing USB devices so that comaptibility issues may be resolved and improvements to device performance may be achieved.
The majority of USB host drivers are developed by either Intel or AMD (processor manufacturers) because USB hosts communicate solely with their respective peripheral devices and the processor.
The improvements made to USB system drivers are distributed in packages called driver updates.
If the driver is not present or has become corrupted, the device may behave unexpectedly or may not function at all.
USB device driver errors can most easily be corrected by updating the driver, yet many users have experienced further errors due to improper driver installation or attempting to replace the USB device driver with the incorrect driver.
It also explains the importance of keeping your drivers up-to-date and some of the challenges with updating USB Drivers.