Battlements, and the pieces of.
Battlements were designed so that the warrior on top of the wall would be protected, but if it were just a whole wall the warriors wouldn't be able to defend the castle. So they have Corrugation, Corrugation is the teeth like top, In between the ''Teeth'' or Merlons, are Crenels, Crenels are for the purpose of shooting arrows at the enemies. The Merlons, were so the warriors could take cover behind them.
Battlements were designed so that the warrior on top of the wall would be protected, but if it were just a whole wall the warriors wouldn't be able to defend the castle. So they have Corrugation, Corrugation is the teeth like top, In between the ''Teeth'' or Merlons, are Crenels, Crenels are for the purpose of shooting arrows at the enemies. The Merlons, were so the warriors could take cover behind them.