While neither the Quran nor the hadith contain specific references to things that should represent Islam, over time certain colors and symbols have come to be associated with Muslims and the Islamic faith. Rather than derived from scripture, symbols like the star and crescent and the colors typically associated with Islam today are simply the products of centuries of cultural tradition.
The color most strongly associated with Islam is green because it has represented Islam for centuries. Many Islamic countries such as Saudi Arabia and Iran feature the color green on their national flags. Some believe that green was the Prophet Muhammad's favorite color, and it is mentioned in a number of verses in the Quran as the color that will be worn by the inhabitants of paradise.
During the period of the Islamic Caliphate, warring factions took on certain colors to represent themselves. When the Abbassid Caliphate revolted against the Umayyads, they wore black clothing and carried black battle standards as it was thought that the coming of the messiah would be signified by a man with a black banner. Today in Iran, devout Shiite women wear black chador and ayatollahs wear black cloaks, while certain descendants of the Prophet Muhammad wear black turbans.
White is perhaps the second-most associated color with Islam. The color white symbolizes purity and peace and so it is often worn by Muslims attending Friday prayers. Muslims also wear it when performing sacred rites of pilgrimage. The Umayyads chose white for their battle standards when they fought the Abbassid during the Caliphate period, and it has appeared on many Islamic flags since.
Although red is often also associated with Islam, it does not have any particular religious significance. Red was featured on Muslim battle standards, which may be why it appears on some national flags today. The color red may also have come to be associated with Islam because in Muslim countries the International Red Cross has used the red crescent symbol on its flags since 1876.
Star and Crescent
In addition to colors, the star and crescent is also symbolic of Islam. From adorning Muslim mosques to an array of Islamic flags, the star and crescent is a rich part of the Islamic culture even though it did not originate in Islam. The star and crescent symbol dates back to the Ottoman Empire. As the Ottoman Turks were introduced to and began to embrace Islam, the star and crescent symbol, which was part of their flag, was gradually associated with Islam as well. Today the symbol is commonly used in a variety of Islamic flags and even in business logos.