Islam is a major world religion with millions of followers, ranging from all over the world. The followers of Islam are Muslims, and follow the five pillars of faith. The five pillars are; Pillar One: Shadah, Pillar Two: Salah, Pillar Three: Zakah, Pillar Four: Sawm, and Pillar Five: Haji. The word Islam means "surrender" or "submission", and salam which means "peace" is the root word of Islam. "Allah" is the Arabic word for god, and Muslims believe that Allah is also the true name of god. Islam is a monotheistic religion, meaning that they only believe in one god. Islam has been around since Adam and Eve, and traces its roots through Prophet Abraham. The first and most well known of Islam's sacred books is the Quran. The holy city is Mecca, which was declared the holiest site in Islam. All Muslims are required to take a pilgrimage to Mecca if they have the means to do so. For a Muslim, the purpose of life is to live in a way that is pleasing to Allah so that one may gain Paradise. It is believed that at puberty, an account of each person's deeds is opened, and this will be used at the Day of Judgment to determine his eternal fate. The Quran also suggests a doctrine of divine predestination. They pray every day, and have a fasting were they do not eat from the time the sun rises till the sun sets. They also pray in the direction of Mecca three times a day. The two major sects of Islam are the Sunni and the Shi'a sects. Muhammad was their leader, and after he had passed, Abu-Bakr became the first caliph, and then three more people who knew Muhammad became caliphs. A caliph means "successor" or "deputy". They expanded the Muslim empire, and by 750 it stretched of 6,000 miles. The holy structure in Mecca is the Kaaba, polished smooth by the hands of thousands of Muslims who come for their pilgrimage.