What causes knocking in IC engines and how can it be prevented?

Knocking occurs when unburned fuel-air mixture auto-ignites ahead of the flame front due to high temperature and pressure, creating pressure waves that cause a metallic pinging sound and can damage engine components. Prevention methods include using higher octane fuel, reducing compression ratio, retarding spark timing, using cooler intake charge (intercooling), enriching mixture during high loads, and employing knock sensors with ECU-controlled timing adjustment. Modern engines use knock detection for real-time optimization.