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Wall wart is a slang term for certain types of power supply - typically those that are embedded in an over-sized AC plug and typically packaged with electrical devices that do not contain their own power supply. This can be for reasons of size of the device, keeping a source of heat remote from the device, making one device for international sale with a variety of power sources; and in the United States due to the economics of getting devices including an internal power supply certified by bodies such as the FCC.

These plugs have come under much derision, hence the name wall wart. Problems with this type of power supply include:

• Size - the power supply may obscure other power points;
• Weight - the weight of the power supply may cause it to fall out of the power socket (this depends on the socket design of the country in question);
• Inefficiency - typically wall warts waste a lot of electricity, both through poor design of the transformers, and the fact that they use power even when the attached device is not in use or even present.

The problem of inefficiency of power supplies has become more well known, with George Bush referring to such devices as "Energy Vampires" responsible for up to 4% of energy use in US homes. Legislation is being enacted in a number of states including California and the EU to reduce the level of waste caused by these devices.

• Bush Takes Aim at "Wall Warts" - Extreme Tech article
• Wall Warts - Embedded.com discussion of the problem of wall warts with much discussion about a possible way of replacing them.
• Google Pushes for PC Electrical Efficiency; Side Effect: No More Wall-Warts - Treehugger.com article on Google statement on power use of electrical devices