Variable Valve Timing (VVT) dynamically adjusts engine valve timing to optimize performance, fuel efficiency, and emissions across operating conditions. Using hydraulic/electric cam phasers, it alters intake/exhaust valve timing and overlap, overcoming fixed-timing compromises. Combined with variable valve lift (VVL) technologies like VTEC and Valvetronic, VVT reduces pumping losses, enhances combustion, and enables precise EGR control. Essential for modern engines, VVT drives 5-10% fuel gains, emissions compliance, and broader torque curves, evolving toward faster electric actuation and camless systems for ultimate flexibility.