Islam could very well be listed as the fastest growing religion in the world today. This means that about 1 out of every 5 people on Earth is a Muslim. This population extends to 40 countries on 3 continents. The division arose over a dispute that concerned the succession of leadership after Mohammed's death. The 2nd disagreement concerned the doctrine of lmam.
New ones appear from time to time as they are needed.
Throughout the history of Islam, men have claimed this position. The Sunni's believe that the imam is just the leader of the Friday night prayer service and nothing more. The Sunniites make up the majority of the population in countries such as Egypt, Saudi Arabia, and Pakistan. The Shiites populate Iran, Iraq, Lebanon, and parts of Africa and are the fundamentalists that we bear about so often on the news. They are also very active in the war for the Holy Land.