Demystifying the Power Button and its On/Off Symbols


As technology has become an essential part of our daily lives, we’ve grown accustomed to certain ubiquitous symbols present on our devices. One such symbol is the power button with its associated on/off symbols. To better understand this crucial component, let’s explore the evolution and significance of the power button and examine the on/off symbols that accompany it.

The History of The Power Button:

The power button’s roots can be traced back to the mechanical switches used in early electronic devices. As technology progressed and device sizes decreased, there arose a need for more convenient methods of powering electronic gadgets on and off. The now-familiar power button symbol was designed as a universal language for device users to easily identify and control device power independent of cultural or language barriers.

The On/Off Symbols:

The power button typically features two common symbols: a vertical line enclosed within a circle ─ referred to as “I” (for “On”) ─ and a small circle, similarly enclosed ─ referred to as “O” (for “Off”). These visually distinct symbols allow users to quickly determine whether their device is switched on or off, regardless of prior experience with electronics.

The IEC 5009 Standard:

To ensure consistency and global recognition, the International Electrotechnical Commission (IEC) introduced the IEC 5009 standard, which defines the power button symbol we see today. According to this standard, a broken circle with a vertical line within signifies a power switch that can be toggled on or off. Device manufacturers worldwide adhere to this specification, making power buttons easily identifiable regardless of their geographical origin.

Power Button Functions:

While the primary function of a power button is to turn devices on or off, it can also deliver further functionality in many modern electronics. Pressing and holding the power button often triggers additional features or information displays. For example, smartphones can provide options like restarting or powering off, while computers may display menu options for various systems settings.


From its humble beginnings as a mechanical switch, the power button has evolved to become an essential and easily identifiable component in electronics. Thanks to standardization efforts by organizations like the IEC, the power button and its on/off symbols have transcended language and cultural barriers to provide consistent user experiences across devices. So the next time you power on your gadgets, take a moment to appreciate this tiny but crucial element that keeps our tech-laden lives running smoothly.