ELI5: Explain Like I'm 5

din rail

Din rail is a metal rail that's used for attaching and mounting switches and electronic controls onto walls. It's called "din rail" because it's made from a type of metal called din steel. When devices are mounted onto it, they stay in place because the holes on the devices match up with the notches on the rail. Din rails are usually seen in industrial settings, like the inside of factories, because they make it easy to organize and mount lots of switches and electronic controls.