Is the line 'on' or is the 'O' 'on'?

[VanBrooklyn]

Generally speaking, the horizontal line on a switch represents 'on', while the circle 'O' represents 'off'. Origin of the switch symbols: It is said that this convention dates back to World War II, evolving from the basic definitions of binary 1 and 0. The circle represents an open circuit, i.e., the 'off' state, while the vertical or horizontal line represents a closed circuit, i.e., the 'on' state. After decades of application and evolution, these symbols have now become internationally recognized power switch indicators widely used in production and daily life. Advantages of the switch line: The switch line usually has a glow-in-the-dark feature, making it easier to locate the switch in the dark at night. Typically, the horizontal line is positioned at the top of the switch panel, where pressing down turns it off, and pressing up turns it on.