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A vertical line entering the top of a broken circle — IEC 60417-5009, marking a control that puts equipment into a low-power state rather than fully disconnecting it.
Also known as: Standby symbol, Power button symbol, Sleep symbol, IEC 60417-5009
Sometimes confused with: Power off symbol
The symbol most people call 'the power button'. Registered as IEC 60417-5009 'Stand-by', it denotes a switch or position that places equipment in a low-power standby state; crucially, it does not indicate that power is fully disconnected. The unbroken-circle variant (IEC 60417-5010) is the one that means a true on/off toggle.
Marks a switch or switch position that places equipment into a low-power standby state. The switch does not fully disconnect the equipment from its power supply.
Contexts: Software, Electrical equipment
In everyday use on consumer devices this symbol is read simply as 'the power button', appearing alone on a button that toggles between on and standby — a usage that is now near-universal but is broader than the standard's own definition.
Contexts: Software
Means the device is still drawing power. A circle broken by a vertical stroke that touches or crosses the ring is standby: the machine is listening for a remote, keeping a clock, or holding a network connection. A closed circle with a stroke *inside* it and not touching is the power toggle, which is a different claim about what happens when you press it.
Contexts: Software, Electrical equipment
Related forms that are not treated as separate canonical symbols — see our variant rules.
Unicode POWER SYMBOL
U+23FB, encoded in 2014 after a proposal specifically to bring the IEC power marks into the standard.
Crescent-moon sleep form
A crescent moon used on many computers for a sleep state rather than standby. Not an IEC symbol, and conventional rather than defined.
A circle with a small gap at the top, and a short vertical line rising from that gap through the circle's edge. The gap is what distinguishes it from the on/off toggle symbol, whose circle is closed.
Near-identical: a broken circle means standby, a closed circle means a true on/off toggle. The difference is a gap a few pixels wide but changes whether power is actually disconnected.
Routinely read as 'off', but this symbol leaves the equipment connected to its supply — the plain circle is the one that means power is genuinely disconnected.
Both belong to the IEC 60417 equipment markings system.