The creation of golems is a secret art passed secretly in Judaism. By imbuing mud or clay with extremely complex magic and then molding it into the desired shape, you can create a Golem. The Golems are able to move and to have a sapienic behavior, they even get to develop feelings.
In order to maintain themselves, the Golems are sustained of the magical power of its creator. Because of this, only very powerful witches are able to use them, since if they are made by a witch without much magic power, the Golem will occupy all its power and the witch in question will be unable to use magic.