What is hydroplaning (aquaplaning), and what should you do if your vehicle begins to hydroplane on water?

1. When tires lose contact with the road and ride on a film of water; ease gently off the accelerator and hold the steering wheel straight without hard braking
2. When the radiator overheats; immediately turn on the air conditioner
3. When brake fluid boils; pump the parking brake aggressively
4. When tires expand in heat; pull onto the grass immediately