The star and crescent is the best-known attribute used to represent Islam. It appears on the flags of many countries in the Islamic world, like Turkey and Pakistan.
Surprisingly, this symbol is not Muslim in origin. Rather, it was a polytheistic icon adopted during the spread of Islam, and its use today is sometimes contraversal in the Muslim world. The crescent and star are generally said to be Islamic symbols, but historians say that they were the insignia of the Ottoman Empire, not of Islam as a whole.