Windows Hardware Quality Lab (WHQL) testing is a Microsoft testing process designed to prove to Microsoft, and ultimately to the customer, that a particular hardware
or software item will work satisfactorily with Windows.
Drivers are also commonly tested by Microsoft so they can be WHQL certified and is probably where you'll encounter the WHQL term most often.
Drivers that have been WHQL certified avoid the warning message during the driver installation process that says that the driver being installed was not certified by Microsoft.
See How To Update Drivers for more information on installing drivers.
You can stay up to date on the latest WHQL driver releases from major manufacturers on my Windows 8 Drivers and Windows 7 Drivers pages.
Also Known As: Windows Hardware Quality Lab
Examples: "I had a beta driver for my video card installed but I updated to the WHQL version as soon as it was available."