The Star of David , known in Hebrew as the Shield of David or Magen David is a generally recognized symbol of Jewish identity and Judaism. Its shape is that of a hexagram, the compound of two equilateral triangles. One triangle represents the ruling tribe of Judah and the other the former ruling tribe of Benjamin. It is also seen as a dalet and yud, the two letters assigned to Judah. There are twelve Vav, or "men," representing the twelve tribes or patriarchs of Israel. The hexagram has been in use as a symbol of Judaism since the 17th century. The term "Shield of David" is also used in the Siddur (Jewish prayer book) as a title of the God of Israel.