A class driver is a general driver that serves every device following a particular standard, such as USB audio or mass storage, so that individual makers do not need to write a driver for each product.
In practice
Windows includes class drivers for keyboards, mice, webcams, many audio interfaces and storage devices. A new thumb drive works immediately because the mass-storage class driver handles any device following that standard.
Common confusion
A class driver is not a lesser or temporary driver. For many devices it is the intended long-term solution. It does, however, expose only features defined by the standard, so maker-specific extras require additional software layered above or beside it.
Why it matters to readers
Recognising a class driver in the Driver tab, usually provided by Microsoft, explains why a device works without a maker package and helps you judge whether any maker package would add something you need.
A closer look
Some class drivers work with small companion modules called minidrivers. The class driver handles everything common to the category, while the minidriver supplies the details of one product family. Audio and printing frequently follow this pattern. The arrangement lets makers provide device assistance for their products with relatively little code and benefit from improvements Microsoft makes to the shared class driver.
