We all know the symbol of a circle with a vertical line through it as the ubiquitous power-on button; used on virtually every electronic device on the planet. So what's the origin of this strange symbol?
Originally, machines were powered by a switch or lever, each side marked with the words "on" and "off." As switches became smaller and more global, the two words were replaced with a 1 and 0, which refer to closed circuit/open circuit, respectively. Then the switch was gradually replaced by the push-button, and the 1 and 0 were combined into the symbol we have today. The symbol, although having been around earlier, was made the official activation/deactivation symbol by the IEC (International Electrotechnical Commission) standard in 1973. I don't know if this is intentional or not, but I also think the symbol resembles a person's finger pressing a button.
Nobody knows who actually created the symbol or where it was first used. I find this ambiguity of origin fascinating!