"The word Imam has multiple connotations. In Sunni Islam, the imam is merely the person who stands at the head of the mosque and leads the congregation in prayer. While the Shi'ah sometimes employ this definition for their religious leaders as well, they also recognize a "fixed" number of Imams--the number of whom depends on the sect of Shi'ism--who, as the Prophet's legitimate successors, bear the responsibility of guarding and preserving Muhammad's divine message."