AC power connectors and sockets are devices that allow electrically operated devices to be connected to the primary alternating current (AC) power supply in a building. Electrical plugs and sockets differ in voltage and current rating, shape, size and type of connectors. The types used in each country are set by national standards.

Generally the plug is the movable connector attached to an electrically operated device's power cord, and the socket is fixed on equipment or a building structure. Plugs have male circuit contacts, while sockets have female contacts. The plug has protruding prongs, blades, or pins that fit into matching slots or holes in the socket. A socket is also called a receptacle, outlet, or power point. It is enclosed by a cover variously called a wall plate, face plate, outlet cover,socket cover, or wall cover.

To reduce the risk of electric shock, plug and socket systems have safety features. For example, sockets can be designed to accept only compatible plugs in the correct orientation, and reject all others. Plugs may have insulated sleeves on contact pins so that energized pins can never be touched during insertion of the plug. Some sockets have shutters to block insertion of objects other than compatible plugs. Sockets are designed to prevent exposure of bare live contacts. The exposed contacts present in some sockets are used exclusively for grounding (earthing).

Types in present use

There are two basic standards for voltage and frequency in the world. One is the North American standard of 120 volts at a frequency of 60 Hz, and the other is the European standard of 220–240 volts at 50 Hz. The differences arose for historical reasons as discussed in the article Mains electricity. Usually NEMA type receptacles and plugs are used on 60 Hz systems, and CEE and other types are used on 50 Hz systems, but exceptions exist. The outline maps show the different plug types, voltages and frequencies used around the world,color-coded for easy reference.

Socket types are sometimes designated by an arbitrary letter designation from a 1998 US government publication, which has no official standing but is sometimes useful as a de facto naming standard when comparing different AC power connectors and sockets.

In Europe, the European Committee for Electrotechnical Standardization (CENELEC) publishes a list of approved plug and socket standards used in the member countries