The shape is that of the crescent moon, a traditional magical symbol. It was also used to ward of fairies, the devil, evil spirits, as well as the evil eye.

It was nailed above the doorway into the house, church, stable or buildings. They might also be placed in the chimney so that witches could not fly down the chimney on their brooms.

The horseshoe to ward of witches must point downwards where if it is for luck it must be pointed upwards.