The Star of David, Magen David or hexagram is the most recognisable and universal symbol of world Jewry. However this hasn't always been the case. The history of the Star of David is long and confused.

What does it look like?

The Star of David is formed from two equilateral triangles. One is pointing up, and the other crosses over it, pointing downwards. The effect is a star such that all its points would touch an enclosing circle. The triangles are sometimes depicted as entwined, and the motif can be varied in a number of ways provided the 'two triangles, six points' theme is maintained.

If your browser can display it, it looks like this:
(Thanks to caknuck for the symbol)

History and confirmed uses

The earliest known use of a Jewish Star of David is in Ancient Israel on a seal, circa 6th Century BCE. The next discovered one is as decoration in a synagogue in Capernaum, dated at around the 3rd Century.

Stars of David pop up all over Europe and the Middle-East during dark ages and middle ages. They appear on churches, graves and mosaic patterns. It was also used by the Karaites in protective amulets. However, they are not at this point a specifically Jewish symbol; the Menorah and the Four Species are used instead.

In 1354, King Charles IV granted the Jewish community in Prague the right to have their own flag. We know that by the 17th Century, this flag was a hexagram, and there is no record of it being changed, so it is possible -- likely, even -- that this flag used a Magen David from its 14th Century inception. It is also in this period that the Jews of Europe went through a particularly superstitious period, with charms and amulets becoming very popular. The Magen David was a common theme on these charms, borrowed from its use in practical Kabbalah.

Exactly at what point the Star of David switched from being a fringe symbol to the mainstream emblem for Jews worldwide isn't clear, but it must have occured somewhere between the 17th and 19th centuries. The synagogue in Bristol, UK, built in 1871, is decorated with a Star of David motif all over it. This is the case for lots of contemporary synagogues and Jewish buildings. One suggestion is that the Star of David represented a simple, easy-to-draw symbol, lacking in heavy religious or historical baggage, that could be easily adopted. Some have suggested that its adoption was party inspired by the use of the Cross as a quick mnemonic for Christianity, and that the Jews saw its uses, or even that Christian architects began using it on synagogues they designed in much the same way as they used Crucifixes on churches.

Theodor Herzl in 1897 incorporated the star into the flag of the Zionist movement. He wanted a flag with seven of these stars (possibly filled in) in gold on a white background. The design actually adopted by the Zionist Congress in 1897 was a blue Star of David on a white background, with blue stripes above and below. This became the flag of the state of Israel. One of the reasons the early Zionists chose this symbol was because, unlike the Menorah, it represented the Jewish people without having specific religious connotations. In 1898, in London, the symbol was formally named "Star of David".

The Nazis used this symbol as a mark of Judaism, and forced Jews to wear Yellow Stars; black Stars of David on a yellow background, with 'Jew' written in the middle.

Legends and meanings

The most persistent legend -- the one taught to children at Jewish kindergartens -- is that the Magen David (lit: Shield of David) was literally that; the design found on the shields of the army of King David. It is understandable where this explanation might come from. The word "David", written in pre-Hebraic script, begins and ends with a triangle-symbol (like the Greek delta). So the shield-design might be seen as a form of David's name. Maintaining the shield theme, there are some suggestions that the symbol was formed by bracing struts on the reinforced shields used during the bar Kochba revolts.

There is, however, no source for these explanations older than the 20th century.They are probably post-rationalisations. In all likelihood, the name 'Magen David' arose from its use in 13th Century kabbalah as a symbol of protection. The association with David is unclear. The symbol is sometimes called the Seal of Solomon (also often used to refer to the Pentagram). It is linked to various parts of the Solomon legends, often as the sign on his (or Asmodeus's) ring.

The specific symbolism of the Star is also unclear. Mystics suggest it represents balance between Above and Below, or fire and earth, or even male and female. However, it's possible it has no symbolism other than looking pretty.

There is a tendency by certain political groups to portray the Star of David as a Zionist political symbol and therefore 'fair game'. Signs and graffiti equating the Star of David with a Swastika are commonplace, and the famous cover of the New Statesman in January 2002 showing a gold Star of David piercing a Union Jack under the headline "A Kosher Conspiracy". This association is seen as profoundly distasteful by Jews, as they associate the Star of David not with Israel or Zionism but as a national and religious symbol of identity.

Similarly, the Magen David Adom (Red Star of David) is the ambulance service of Israel. It is denied entry into the International Committee of the Red Cross because only services displaying the Cross or Muslim Crescent are allowed to join.
Joseph Heller, God Knows, 1984
The New Standard Jewish Encyclopedia, Geoffrey Wigoder ed. 1992