The Sign Of Islam
The crescent moon and the star is a symbol of Islam known all over the world. Our symbol is shown on flags, of several Muslim countries. We as Muslims have the crescent moon and the star, as Christians have the cross, and the Jewish people have the star of David.
The crescent moon and star symbol actually pre-dates Islam by several thousand years. Information on the origins of the symbol are difficult to ascertain, but most sources agree that these ancient celestial symbols were in use by the peoples of Central Asia and Siberia in their worship of sun, moon, and sky gods.
The early Muslim community did not really have a symbol. During the time of the Prophet Muhammad (peace be upon him), Islamic armies and caravans flew simple solid-colored flags (generally black, green, or white) for identification purposes. In later generations, the Muslim leaders continued to use a simple black, white, or green flag with no markings, writing, or symbolism on it.
It wasn't until the Ottoman Empire that the crescent moon and star became affiliated with the Muslim world. When the Turks conquered Constantinople (Istanbul) in 1453, they adopted the city's existing flag and symbol. Legend holds that the founder of the Ottoman Empire, Osman, had a dream in which the crescent moon stretched from one end of the earth to the other. Taking this as a good omen, he chose to keep the crescent and make it the symbol of his dynasty. There is speculation that the five points on the star represent the five pillars of Islam, but this is pure conjecture. The five points were not standard on the Ottoman flags.
So, the crescent moon is a sign of faith and the five points on the star are representing the five pillars of islam.