All-wheel drives are often referred to as "AWD" or "four-wheel drives" (4WD). In some cases, they may also be called "full-time four-wheel drives" or "permanent four-wheel drives". Additionally, certain vehicle manufacturers have their own branded versions of the technology, such as Subaru's "Symmetrical All-Wheel Drive" and Audi's "Quattro System". All-wheel drives act as a safety feature for drivers in inclement weather conditions, as they provide more traction and stability. As such, the term is frequently used in automotive marketing materials, car reviews, and discussions among car enthusiasts.