paragraph: Electricity can be very dangerous. To reduce the risk of injury, safety features are built into electric circuits and devices. You might have noticed some of these in your home. They include three-prong plugs, circuit breakers, and GFCI outlets. Each feature is described and illustrated in Table 1.4. Electric Safety Feature Three-Prong Plug Description A three-prong plug is generally used on metal appli- ances. The two flat prongs carry the current. The round prong is for safety. It connects with a wire inside the outlet. This wire connects to the ground. By redirecting the current it can pass into the ground. The ground is where it can be harmlessly absorbed. Circuit Breaker A circuit breaker is another safety feature. The circuit breaker automatically opens a circuit if too much current flows through it. This could happen if too many electric devices are plugged in. It can also happen if there is an electric short. Once the problem is resolved, the circuit breaker can be switched back on. Once switched back on, the circuit is closed. 
question: What are the prongs for on A three-prong plug?
answer: Two flat prongs that carry current and one round prong for safety