Shiite is sect of Islam, which means "Ali's supporters". Shiites consider There (the cousin and son-in-law of the prophet Mohammed) the legitimate successor to the Islamic authority.
The Shiite sect considers the Sunnis, another sect of Islam, who took over the leadership of the Muslim community after Muhammad's death, to be illegitimate. Initially, the Shiites were a political faction that supported the power of Ali Abu Talib, then, after becoming his successor, it ended up being murdered, and from then on, the Shiites felt obliged to defend the religious and political legitimacy of their descendants.
Shiites are present in several countries around the world, but there are some where they are the majority, such as Iran, Iraq, Pakistan, Saudi Arabia, Bahrain, Lebanon, Azerbaijan, Yemen and others. Shiites cannot be confused with a specific religion, they are members of Islam, and have become just a sect with another line of thought.
The Shiite sect, composed of followers of Ali (cousin and son-in-law of Muhammad) only recognize Ali and his descendants as caliphs. Unlike the Sunnis, they considered the imam as the mediator and head of the divine nature and also believed in an imam still hidden and yet to come (Mahdi).
The Shiites are divided into various sects (Zaidites in Yemen, Ismailis in Iran and India, Imanites in Syria) and are very numerous, especially in Iran.
You duodeciman Shiites they consist of the most numerous sect and are also known as the Twelve-Iman Shiites. This sect believes that there were twelve successor imams of Mohammed and that the twelfth is hidden and when revealed will rule the Muslim world.
Sunnis
The opposite of the Shiite are the Sunnis. Sunnis believe that Muhammad had no legitimate heir, and that the successor should be elected by a vote among the people of the Islamic community. Most Muslims are Sunni. The biggest conflicts between sects are political conflicts, and Sunnis are known for their anti-government protests and car bombs.