What is an all-wheel drive (AWD) system and how does it work?

All-wheel drive distributes power to all four wheels simultaneously, improving traction on various surfaces. AWD systems include a center differential or transfer case to split power between front and rear axles. Full-time AWD always drives all wheels, while on-demand AWD primarily drives one axle and engages the other when slip is detected. AWD improves acceleration grip and stability but adds weight, complexity, and reduces fuel efficiency compared to two-wheel drive.