Have you ever noticed the Power Button (On/Off Switch) in your computers, and electronic devices?
You would find below symbol which are normally known as Power Button (On/Off Switch). Technically, this symbol was used to denote Standby and not for Power. This was wrongly used by all leading manufacturers.
In order to resolve this ambiguity, IEEE made some corrections to the symbols and introduced a new symbol called Crescent in 2004.
According to IEEE,
Bonus: Microsoft still using the old Power Symbol for shut-down in Windows 7. FAIL