There are about 1.6 billion Muslims or 23% of the world's population. The two main sects of Islam are the Sunnis and the Shi'ites. The difference between them is they wordhip differently and there is more of a political difference than a creed difference. The major holidays of islam is Ramadan and Hajj. Muslism came to America with the African slaves. While muslims might not be the majority religion in the united States, it dominates other parts of the world, especially Macedonia.