A driver is a small piece of software that translates between the operating system and a specific piece of hardware. Without one, the system knows something is plugged in but has no idea how to use it properly.
Because drivers sit so close to the hardware, their faults look like hardware failure: a screen that flickers, audio that crackles, a touchpad that ignores gestures, or a printer that prints garbage.
Newer is not always better. A graphics driver released last week can regress on older hardware, and a generic driver installed automatically may lack the features of the manufacturer's own version.
The reliable approach is targeted: update the driver for the part that misbehaves, from the manufacturer's site, and roll back if the new version makes things worse.