Islam -- a brief overview

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(CNN) -- Islam is one of the world's major religions, along with Hinduism, Judaism, Buddhism and Christianity.

Since its birth in Arabia more than 1,400 years ago it grew rapidly, making a profound impact on philosophy, literature, the arts, science and medicine throughout history.

Today, an estimated 1.1 billion people worldwide are Muslims and the Islamic traditions they follow are as varied as the nations where they live.

Islam's central teaching is that there is one all-powerful, all-knowing God, who is referred to by the Arabic name, Allah. In Arabic, Islam means "surrender," or "submission," to the will of God.

Islam was founded by the prophet Mohammed, who was born in Mecca around A.D. 570 and settled in Medina around 622. Muslims believe Mohammed was the last and most important in a series of prophets, including Abraham, Moses and Jesus.

The holy book of Islam is the Koran, which means "the timeless words of God."

The core practices are known as the Five Pillars -- daily prayer, faith, fasting, pilgrimage and alms giving.

Performing the Hajj is the fifth pillar of Islam. Hajj means to set out for a place and for Muslims that place is Mecca. It is mandatory for every Muslim to make the journey at least once in a lifetime. Over 2 million Muslims made the pilgrimage in 2005.

The two main branches of Islam are Sunnism and Shi'ism.