ELI5: Explain Like I'm 5

Rotation number

A rotation number is like a person's turn in a game. It is a way of knowing how many times a person has gone in order. Think of it like a round in a game or race. All the players start at the beginning and everyone takes turns to go. The rotation number is just the order in which everyone goes. It usually starts with 1 and each time it goes up by 1 until it gets back to the beginning.