The Hot Slot
The smaller of the two slots is the one on the right. It is the "hot" part of the receptacle, meaning that electrical current flows from the breaker box to the appliance via this slot.
The Neutral Slot
The larger of the two slots, the one on the left, is the "neutral" (or "common") slot. Current that has left the hot slot travels through the appliance and returns through the common slot, closing the circuit. If the "hot" slot is like a faucet pouring out current, the "common" slot would be comparable to the drain carrying current away.
The U-shaped hole is for an appliance's grounding prong and provides a route for the electrical current to go to ground in case of a short circuit, when the current does not flow properly from "hot" to "neutral."
Receptacles are connected to three-wire electrical cable with one of two common methods: the ends of the wires are either wrapped around terminals and tightened with screws, or they are pushed into clips in the back of the receptacle.
Regular interior-use outlets are rated for 15 amps of current and 125 volts. They can handle common appliances like stereos, lamps and fans. Appliances that draw more power than that, such as air conditioners or electric clothes dryers, require different types of outlets with higher ratings.