A power symbol is a symbol

Symbol

A symbol is something which represents an idea, a physical entity or a process but is distinct from it. The purpose of a symbol is to communicate meaning. For example, a red octagon may be a symbol for "STOP". On a map, a picture of a tent might represent a campsite. Numerals are symbols for...

 indicating that a control activates or deactivates a particular device. It incorporates line and circle figures, with the arrangement informed by the function of the control. The universal power symbols are described in the International Electrotechnical Commission

International Electrotechnical Commission

The International Electrotechnical Commission is a non-profit, non-governmental international standards organization that prepares and publishes International Standards for all electrical, electronic and related technologies – collectively known as "electrotechnology"...

 60417 standard, Graphical symbols for use on equipment, appearing in the 1973 edition of the document (as IEC 417) and informally used earlier.

Definitions

	button Button (control) A push-button or simply button is a simple switch mechanism for controlling some aspect of a machine or a process. Buttons are typically made out of hard material, usually plastic or metal. The surface is usually flat or shaped to accommodate the human finger or hand, so as to be easily depressed...  or one end of a toggle switch indicates that the control places the equipment into a fully powered state. It comes from the binary system (1 or > means on)
	IEC 5008, the power off (circle) symbol on a button or toggle, indicates that using the control will disconnect power to the device. It comes from the binary system (0 means off)
	IEC 5010, the power on-off symbol (line within a circle), is used on buttons that switch a device between on and fully off states.
	IEC 5009, the standby symbol (line partially within a broken circle), indicates a sleep mode Sleep mode Sleep mode refers to a low power mode for electronic devices such as computers, televisions, and remote controlled devices. These modes save significant electrical consumption compared to leaving a device fully on and idle, but allow the user to avoid having to reset programming codes or wait for a...  or low power state. The switch does not fully disconnect the device from its power supply Power supply A power supply is a device that supplies electrical energy to one or more electric loads. The term is most commonly applied to devices that convert one form of electrical energy to another, though it may also refer to devices that convert another form of energy to electrical energy... . This may appear on a toggle switch opposite a power on symbol, alone on a pushbutton that places the device into a standby state, or alone on a button that switches between on and standby. Alternatively, under IEEE 1621, this symbol simply means "power".
	A crescent moon Moon The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more... , indicating sleep, is added by IEEE 1621 as a replacement for the standby symbol.

Standby symbol ambiguity

Because the exact meaning of the standby symbol on a given device may be unclear until the control is tried, it has been proposed that a separate sleep symbol, a crescent

Crescent

In art and symbolism, a crescent is generally the shape produced when a circular disk has a segment of another circle removed from its edge, so that what remains is a shape enclosed by two circular arcs of different diameters which intersect at two points .In astronomy, a crescent...

 moon, instead be used to indicate a low power state. Proponents include the California Energy Commission

California Energy Commission

The California Energy Commission is California’s primary energy policy and planning agency. Created in 1974 and headquartered in Sacramento, the Commission has responsibility for activities that include forecasting future energy needs, promoting energy efficiency through appliance and building...

 and the Institute of Electrical and Electronics Engineers

Institute of Electrical and Electronics Engineers

The Institute of Electrical and Electronics Engineers is a non-profit professional association headquartered in New York City that is dedicated to advancing technological innovation and excellence...

. Under this proposal, the older standby symbol would be redefined as a generic "power" indication, in cases where the difference between it and the other power symbols would not present a safety concern. This alternative symbolism was published as IEEE standard 1621 on 2004-12-08.

In popular culture

The standby symbol, frequently seen on personal computer

Personal computer

A personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end-user with no intervening computer operator...

s, is a popular icon among technology enthusiasts. It is often found emblazoned on fashion items including t-shirts and cuff-links (started in 2011). It has also been used in corporate logo

Logo

A logo is a graphic mark or emblem commonly used by commercial enterprises, organizations and even individuals to aid and promote instant public recognition...

s, such as for Gateway, Inc.

Gateway, Inc.

Gateway Computer Corporation, is a computer hardware company headquartered in Irvine, California, USA which develops, manufactures, supports, and markets a wide range of personal computers, computer monitors, servers, and computer accessories...

 (circa 2002), Staples, Inc.

Staples, Inc.

Staples Inc. is a large office supply chain store, with over 2,000 stores worldwide in 26 countries. Based in Framingham, Massachusetts, United States, the company has retail stores, serving customers under its original name in Austria, Brazil, China, France, Germany, India, Italy, Norway,...

 easytech, Exelon

Exelon

Exelon Corporation is an electricity generating and distributing company headquartered in the Chase Tower in the Chicago Loop area of Chicago. It was created in October, 2000 by the merger of PECO Energy Company and Unicom, of Philadelphia and Chicago respectively. Unicom owned Commonwealth Edison...

 and others, and even as personal tattoos. In March 2010, the New York City

New York City

New York is the most populous city in the United States and the center of the New York Metropolitan Area, one of the most populous metropolitan areas in the world. New York exerts a significant impact upon global commerce, finance, media, art, fashion, research, technology, education, and...

health department announced they would be using it on condom wrappers.