Today, there are more than 1.1 billion Muslims in the world. Even in the wake of this enormous growth, many of the practices established by Muhammad remain intact today. This not only applies to how Muslims pray, but also to how they construct their mosques, what events they celebrate, and what music they listen to and play. By adhering to the teachings of the Qur'an, a book that has remained virtually unchanged for hundreds of years, Muslims observe a rich cultural tradition that bridges the past, present, and future worlds of the community of the faithful.