✡

Description
The Magen David: a hexagram (six-pointed star formed by overlapping two equilateral triangles).

Etymology
The precise origin of the use of it as a Jewish symbol remains unknown, but it apparently emerged in the context of medieval Jewish protective amulets (segulot). The Jewish Encyclopedia cites a 12th-century Karaite document as the earliest Jewish literary source to mention the symbol.

Symbol

 * 1) Judaism or Jewish identity.
 * 2)  marks a synagogue.

Usage notes
This shape is generically called a hexagram (which has a wider array of definitions), but this specific symbol has been labelled by Unicode for use as the Star of David.