A leader of prayers or religious leader. The term is used for the spiritual leaders descended from Ameer ul-Mumineen ‘Ali (AS) and Maulatana Faatema (AS), the Prophet's daughter, who are believed to be the legitimate successors to the Prophet. The Imaams are held to be ma'soom, completely immune from sin and error; they are generally held to be also divinely appointed and divinely guided in the discharge of their special spiritual functions. The office of Imaam is known as Imaamat.