We used to have a standard, the Edison plug. Now we only use Edison plugs as the base of light bulbs. Originally, appliances had an Edison plug and screwed into an overhead light socket. An extension cord would thus drop down from the ceiling, which is why many people call them "drop cords." You can find images of old appliances from Sears catalogs showing they had Edison plugs.
We used to have a standard, the Edison plug. Now we only use Edison plugs as the base of light bulbs. Originally, appliances had an Edison plug and screwed into an overhead light socket. An extension cord would thus drop down from the ceiling, which is why many people call them "drop cords." You can find images of old appliances from Sears catalogs showing they had Edison plugs.
History lesson for the day. :)