Though there are many plug types available, generally they conform to either a national or international standard. National standards are unique to every country and relate to the source outlet and mating connectors. For example, NEMA - the National Electrical Manufacturers Association, is the source of plug standards in North America and has developed the two and three prong outlets and plugs. International standards on the other hand, are governed by the IEC or International Electrotechnical Commission and often relate to the connector on the other side of a power cord that plugs directly into the electrical device or power supply.