Mains electricity or utility power, power grid, domestic power, and wall power, or, in some parts of Canada, hydro, 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 differs between regions. In much of the world, a voltage (nominally) of 230 volts and frequency of 50 Hz is used. In North America, the most common combination is 120 V and a frequency of 60 Hz. Other combinations exist, for example, 230 V at 60 Hz. Travellers' portable appliances may be inoperative or damaged by foreign electrical supplies. Non-interchangeable plugs and sockets in different regions provide some protection from accidental use of appliances with incompatible voltage and frequency requirements.
In the US, mains electric power is referred to by several names including "utility power", "household power", "household electricity", "house current", "powerline", "domestic power", "wall power", "line power", "AC power", "city power", "street power", and "120 (one twenty)".
In the UK, mains electric power is generally referred to as "the mains". More than half of power in Canada is hydroelectricity, and mains electricity is often referred to as "hydro" in some regions of the country. This is also reflected in names of current and historical electricity utilities such as Hydro-Québec, BC Hydro, Manitoba Hydro, and Hydro One (one of the entities resulting from the breakup of Ontario Hydro). Although there is an entity named Newfoundland and Labrador Hydro, that company is primarily a hydroelectricity generator, though it also directly serves customers in Labrador and some other parts of the province. The majority of customers on the island of Newfoundland deal with Newfoundland Power as their service provider, and thus electricity is more commonly called simply "power" in that province.