The power button, which is used to turn a device on or off, resembles a small circle with a vertical line.
The symbol is believed to have originated as technology improved, and the term ‘On and Off’ was replaced by the universal numeral symbols 1 and 0.
The numbers were derived from the Binary Number System, in which 1 stands for power and 0 indicates power off.
To create the symbol the “1” and “0” symbols were merged with each other, to bypass language barriers.
Source: Inshorts