Some of the older set have trouble figuring out that the on and off button are the same, or that that's what the little circle with a line in it means.
Speaking of which, why is that what a circle with a line in it means? Who came up with that silly symbol?
It's an interrupted circle. Circle and circuit come from the same root word.
It was intended to combine 1 and 0 to symbolize on and off.
Blame the International Electrotechnical Commission. Yes, that is correct, it really was designed by a committee, and a committee composed of people with no common language at that!