Islam
Islam means "submission". It holds that the true name of God is Allah and that Mohammed is his prophet. True followers of islam seek to follow the sayings of Mohammed as recorded in the Qu'ran. Most muslims also recognise the "Hadeeth" as an authoritative book governing muslim life, but some muslims are against the Hadeeth and deny its authority in matters of life and faith.
There are around 1 billion people who would call themselves muslim, though the percentage of those who seek to follow the Qu'ran literally would be much smaller.