Full-Time Four-Wheel Drive (4WD) is a drivetrain system that powers all four wheels of a vehicle simultaneously. This setup enhances traction and stability, making it ideal for off-road conditions or slippery surfaces. Unlike part-time 4WD, which requires the driver to engage the system manually, full-time 4WD operates automatically, providing continuous power to all wheels. Vehicles equipped with full-time 4WD often feature a center differential, allowing for differences in wheel speed between the front and rear axles. This design helps prevent tire wear and improves handling on various terrains. Common examples of vehicles with this system include SUVs and trucks.