According to Wikipedia:
Islam – is a religion articulated by the Quran, a text considered by its adherents to be the verbatim word of God (Allāh). It is the world’s largest second religion and the fastest growing major religion in the world, with over 1.7 billion follower or 23% of the global population, known as Muslims. Islam is an Abrahamic monothestic religion that upholds that God is one and incomparable and that the purpose of existence is to worship God. Muslims consider Muhammad to be the last prophet of God.
Muslims also believe that Islam is the original, complete and universal of a primordial faith that was revealed many times before through prophets including Adam, Noah, Abraham, Moses and Jesus. As for the Quran, Muslims consider it to be the unaltered and final revelation of God. Religious concepts and practices include the five pillars of Islam, which are obligatory acts of worship, and following Islam law, which touches on virtually every aspect of life and society, from banking and welfare to women and the environment. Certain religious rites and customs are observed by the Muslims in their family and social life, while social responsibilities to parents, relatives, and neighbors have also been defined. Besides, the Quran and the sunnah of Muhammad prescribe a comprehensive body of moral guidelines for Muslims to be followed in their personal, social, political, and religious life.
Most Muslims are of one of two denominations: Sunni (75–90%) or Shia (10–20%) Read more on Islam denominations