There are four different schools of jurisprudence within Islam. Much blood has been spilt over disputes between them. The main schools are:
Followers of the Hanafi school are called Sunni Muslims and constitute a 90% majority of the believers. They are considered to be main stream traditionalists. Because they are comfortable pursuing their faith within secular societies, they have been able to adapt to a variety of national cultures, while following their three sources of law: the Qur'an, Hadith and consensus of Muslims. Followers of the Jafri school are called Shi'ite Muslims and constitute a small minority of Islam. They split from the Sunnis over a dispute about the successor to Mohammed. Their leaders, Imams promote a strict interpretation of the Qur'an and close adherents to its teachings. They believe in 12 heavenly Imams (perfect teachers) who guide the faithful from their locations in Paradise.
There are over 70 other groups which originated within Islam and broke away from the Sunni and Shi'ite faith communities:
After his death, the community elected a series of Khalifas (successors). The current and "Fourth Successor (Khalifatul Masih IV), to the Promised Messiah was chosen in the person of Hazrat Mirza Tahir Ahmad" on 1982-JUN-10. The Ahmadiyya Community currently has more than 10 million members worldwide. They are very heavily persecuted in Pakistan.