This was a topic I had written an office blog on quite a while back, and just thought I’d share it here as well

In the world of Electronics, nothing comes close to attaining the status of being ‘Truly Omnipresent’ than the humble Power button. From your mobile phone to your TV remote control, laptops to washing machines, if there is anything that consumes electricity, you bet our man will be there. Even though the importance of the Power button need not be stressed, and we use it ever so frequently, do we actually know what the symbols on the power buttons mean, and how it got there?

History

It is said that early Power buttons were marked in English as ON and OFF. Why shouldn’t it be, as it appears to be the most obvious and natural way it should have been done? That’s what everyone thought until the following issues were encountered.

The most obvious one was its assumption that everyone who uses these switches knew English. Another issue was that the wording did not make much sense viewed from different angles.

Evolution

This is when the IEC or the International Electro-technical Commission stepped in and recommended two simple symbols to replace the On/Off text. The symbols were: line ‘|’ for ON and circle ‘O’ for OFF. The advantages of this new convention were quite obvious. It was simple enough to break the language barrier, yet easy to decipher properly across different angles.

This standard is still used on power toggle buttons. The symbols are commonly mistaken to be 1 and 0 from the binary digits, but IEC maintains that that wasn’t the intention when they decided on it.

The onslaught of computers and mobile phones also brought in single button toggling. This meant ON and OFF states could be toggled by pushing the same button, which hence needed a new symbol showing both the states. The very-creative IEC took up this challenge and ended up combining the line and circle, resulting in two more symbols bringing the grand total to four.

So why do we need more symbols you ask?? The following sheet should be clear enough in explaining that –

There were also some symbols which weren’t so frequently such as the Crescent moon symbol for ‘Sleep’ and the circular arrow button for ‘Reset’. The later generations of computers do not have a separate button to ‘Reset’ as it is integrated with the existing power button. How this button behaves, is dictated by the user through options provided by the operating system. For example, a user could set it to ‘Shutdown’, ‘Restart’, ‘Standby’ or even ‘Do Nothing’.

So the next time you see a Power button with a weird circular symbol on it, you know EXACTLY what it is meant to do.