Mains electricity is a general-purpose alternating-current (AC) electric power supply. It is the form of electrical power that is delivered to homes and businesses through the electric grid in many parts of the world. People use this electricity to power everyday items—such as domestic appliances, televisions, and lamps—by plugging them into a wall outlet. The voltage and frequency of electric power differ between regions. In North America, the most common combination is 120 V and a frequency of 60 Hz.

Source: Wikipedia