RALEIGH, NC -- Islam is the world's second most-practiced religion, with 1.3 billion followers. Christianity -- the most-practiced -- has 1.9 billion followers.
Learn more about Islam.

A follower of Islam is called a Muslim. A common misconception is that all Muslims are Arab. Eighty percent of the world's Muslims are not Arab. And while most Arabs are Muslim, about 10 percent of Arabs are practicing Christians, Jews, and members of other faiths.

Indonesia has the largest Muslim population in the world, with Pakistan, Bangladesh, India, and Turkey following.

The Quran (also sometimes spelled Koran) is the book Muslims believes contains guidance from God about how to live. Muslims believe the Quran was communicated in Arabic from the Angel Gabriel to the prophet Muhammad.
Read the Quran

Muslims share a core of basic beliefs, called the five pillars. The pillars are translated in a variety of ways.

The first pillar is faith in Allah (the Arabic word for God). The second pillar is prayer. Muslims are required to pray formally five times a day (at dawn, midday, afternoon, evening, and night). The third pillar is giving alms to the poor and sick (also referred to as zakah or zakat). The fourth pillar is fasting. During the month-long period of Ramadan, Muslims refrain from eating, drinking, smoking and sexual activity. The fifth pillar is the pilgrimage to Mecca (referred to as "hajj"). Every Muslim is expected to visit Mecca at least once in his or her lifetime.
Learn more about the Pillars

The Muslim facility for congregational prayers is called a mosque. Ideally, the mosque is also the community center for the Muslim population.

Sources: USA Today, IslamiCity, IslamWorld.net, Beliefnet, Islam: Empire of Faith (PBS)