Imamate in Shia doctrine

In Shia Islam, the Imamah (إمامة) is a doctrine which asserts that certain individuals from the lineage of the Islamic prophet Muhammad are to be accepted as leaders and guides of the ummah after the death of Muhammad. Imamah further says that Imams possess divine knowledge and authority (Ismah) as well as being part of the Ahl al-Bayt, the family of Muhammad. These Imams have the role of providing commentary and interpretation of the Quran as well as guidance. The word "Imām" denotes a person who stands or walks "in front". For Sunni Islam, the word is commonly used to mean a person who leads the course of prayer in the mosque. It also means the head of a madhhab ("school of thought"). However, from the Shia point of view this is merely the basic understanding of the word in the Arabic language and, for its proper religious usage, the word "Imam" is applicable only to those members of the house of Muhammad designated as infallible by the preceding Imam. The Shia further believe only these A'immah have the right to be Caliphs, meaning that all other caliphs, whether elected by consensus (Ijma) or not, are usurpers of the Caliphate as those were political positions not divine positions. All Muslims believe that Muhammad had said: "To whomsoever I am Mawla, Ali is his Mawla." This hadith has been narrated in different ways by many different sources in no less than 45 hadith books of both Sunni and Shia collections. This hadith has also been narrated by the collector of hadiths, al-Tirmidhi, 3713; as well as Ibn Maajah, 121; etc. The major point of conflict between the Sunni and the Shia is in the interpretation of the word 'Mawla'. For the Shia the word means 'Master' and has the same elevated significance as when the term had been used to address Muhammad himself during his lifetime.