Sunnis and Shi'ites for Beginners
LESSON ONE: The Big Picture
Most Muslims the world over follow the Sunni branch of Islam.
BUT: About 10%-15% of Muslims belong to the Shi'ite (also known as Shiite, Shi'a, Shi'ah or Shia) sect. The majority of Muslims in Iran, Iraq, Bahrain, and Azerbaijan ar Shi'ites, and significant Shia minorities in Afghanistan, Kuwait, Lebanon, Pakistan, Saudi Arabia, Syria, and Yemen. 
LESSON TWO: "What's in a name?"
"Sunni" (also "Sunnite") comes from the Arabic word, sunna ("tradition"). 
"Shi'ite" (also Shiite, Shia, Shi'a, Shi'ah and Shiah) derives from the Arabic shiat Ali ("the party of Ali") 
LESSON THREE: The Caliphate
At the Prophet Muhammad's death, Muslims chose a spiritual leader to rule the Islamic state that Muhammad had founded. This leader was the Caliph (from the Arabic for "successor"], who did not claim prophetic power or doctinal authority. Abu Bakr was the first Caliph, who in turn was succeeded Umar, Uthman, and Ali.  Disagreement over these four leaders caused the split between Sunnis and Shi'ites.
Sunnis revere all of these first four Caliphs (Abu Bakr, Umar, Uthman and Ali) as the Rashidun (the Rightly Guided). 
For the Shi'ites, only Ali is recognized as the first legitimate Caliph. Summing up the conflict, Christopher M. Blanchard wrote that "Ali's followers believed that the Prophet Muhammad himself had named Ali as successor and that the status quo was a violation of divine order. A few of Ali's partisans orchestrated the murder of the third Caliph Uthman in 656 AD, and Ali was named Caliph. Ali, in turn, was assassinated in 661 AD, and his son Hussein (680 AD) died in battle against forces of the Sunni caliph. Ali's eldest son Hassan (died 670 AD) is also revered by Shiite Muslims, some of who claim he was poisoned by the Sunni caliph Muawiyah." 
The Caliphate ceased to be a viable institution after the 13th century, after which "Caliph" became a self-aggrandizing title of certain Muslim rulers. Turkish president Mustafa Kemal Attaturk abolished the Caliphate in 1924 as part of his secularization efforts. 
LESSON FOUR: Common Ground
Both Sunnis and Shi'ites share these basic tenets of Islam: 
• Muhammad was the messenger of Allah.
• All Muslims must abide by the Quran (the record of Allah's revelations to the Prophet) and by the Hadith (the sayings of Muhammad and his companions).
• Piety, striving for goodness, and social justice are essential to belief and religious practice.
• The faithful live in accordance with the Five Pillars of Islam:
(1) Shahada, recital of the creed that "There is no God but Allah, and Muhammad is His Prophet;"
(2) Salat, the five daily obligatory prayers;
(3) Zakat,the giving of alms to the poor;
(4) Sawm--fasting from sunrise to sunset during the month of Ramadan;
(5) Hajj-- A pilgrimage to Mecca once during a lifetime, if one is physically and financially able to make the journey.
• Islamic juriprudence, Instead of codified laws, Muslims rely on the Quran, the Sunna (customs of the Prophet) as revealed in the Hadith, Qiyas (analogy), Ijma' (consensus) and Ijtihad (individual reasoning). It is the role of the learned religious leaders to interpret Shari'a, or Islamic law.
LESSON FIVE: Basic Differences
• Sunnis: The imam (leader of the Muslim community) should be selected by communal consensus, on the existing political order and on the candidate's individual merits. Sunni communities have not always practised this concept, and have allowed lay persons to serve as preachers and prayer leaders. Unlike i'ite imams, the Sunni leaders have usually been subordinate to the governments of the countries which they live.
Shi'ites venerate their imams and have a more elaborate and perhaps more powerful religious hierarchy. According to Yahiya Emerick,"the Shi'a imams are a line of mwn whose ultimate ancestor was Ali. Different groups of Shi'as stop at different imams in the family tree and consider their chosen man to be the last last and most authentic final guide. There are Fivers, Seveners and Thelvers Shia's. Each group has diverse religious doctrines." 
Leadership of the Community. For Shiites, the first true leader of the Muslim community is Ali, who is considered an imam, a term used among Shiites not only to indicate leadership abilities but also to signify blood relations to the Prophet Muhammad. As Ali's descendants took over leadership of the Shiite community, the functions of an imam became more clearly defined. Each imam chose a successor and, according to Shiite beliefs, he passed down a type of spiritual knowledge to the next leader. Imams served as both spiritual and political leaders. But as Shiites increasingly lost their political battles with Sunni Muslim rulers, imams focused on developing a spirituality that would serve as the core of Shiite religious practices and beliefs. Shiites believe that when the line of imams descended from Ali ended, religious leaders, known as mujtahids, gained the right to interpret religious, mystical, and legal knowledge to the broader community. The most learned among these teachers are known as ayatollahs (lit. the "sign of God").
• How both sects perfom the daily prayers differs in small ways.
• Sunnis do not accept the Shi'ite Hadith, which includes the sayings of Shi'ite imams, whom members of the sect venearate as divinely inspired.
• Sunni interpretation of Islamic Law relies less on human reasoning than Shi'ite readings. Four regional schools of jurisprudence teach that legal rulings should draw in equal measure upon analogies and the Hadith, and may vary from narrow to broad interpretation of a given issue. In Turkey and other secular nations, the legal opinions of scholars serve as spiritual guidelines without the force of law.
• There is no Sunni equivalent to ths Shi'ite ayatollahs (the name mean "sign of God"), the most learned among the sect's mujtahids (religious leaders). Ayatollahs have the right to interpret not only legal matters but also religious and mystical questions.
• Sunni Islam has not splintered into distinct sects. In Oman, East Africa and in areas of Algeria, Libya and Tunisia, Ibadis are a sect apart from both Sunnis and Shi'ites. They are sometimes mistaken as a branch of the Sunnis because of their similiarities to basic Sunnite beliefs (they have a strong sense of social and racial justice). The puritanical movement known as Wahhabism lies well within the Sunni branch. Wahhabism takes a strictly fundamentalist and orthodox approach to Islam. The movement began in the 18th century in Arabia, at the time of the rise of the Saudi ruling family and today has close tides to the royals. Wahabbis condemn Shi'ites and even Sunnis outside of their movement as heretics.
On the other hand, three Shi'ite sects have drifted from the mainstream:
(1) The Zaydis: For this minority sect, the first five imams of Islam were legitimate. The trouble is that among themselves the Zaydis dispute the identity of that fifth imam. They do not believe that imams are infallible spiritual guides.
(2) The Alawites of Syria and Lebanon: Members of the ruling Assad family are members of this secretive sect. Alawites view the Pillars of Islam as symbolic concepts rather than as binding duties that govern daily life. Their religious calendar blends Muslim and Christian holidays.
(3) The Druze (or Druse): Centered in Lebanon, Jordan and Syria, this offshoot of eleventh-century Ismaili Shi'ite Islam has departed from orthodox Shi'ite beliefs. With a symbolic Islamic framework, the Druze religion has embraced Gnostic and neo-Platonic beliefs.
• Ashura is a holy day observed by Shi'ites alone. Each year, it marks the death of Ali's yonger son, Hussein. Hussein was killed by Sunni forces near Karbala, Iraq in 680. As Shi'ites recall other martyrdoms and persucutions on Ashura, a number of the faithful flagellate themselves in public. Elsewhere, Shi'ites carry models of Hussein's tombs in processions, and plays reenact the death of the young martyr.
RELATED NEWS: Rival Shiite leaders bury the hatchet in peace deal (CNN, October 6, 2007).
• Disclaimer: The author is not a Muslim, nor does he intend this article to be more than a superficial introduction to the Sunni and Shi'ite sects.
 Blanchard, Christopher M. "Islam: Sunnis and Shiites.(Report)." Congressional Research Service (CRS) Reports and Issue Briefs. Congressional Research Service (CRS) Reports and Issue Briefs, 2006. NA. General OneFile. Gale. DISCUS Remote Patron Access ITWeb. Accessed on October 4, 2007.
 "Sunni." The Columbia Encyclopedia. The Columbia University Press, 2000. 37157. General OneFile. Gale. DISCUS Remote Patron Access ITWeb. Accessed on October 4, 2007.
 Bijlefeld, Willem A. "Shiites." Grolier Multimedia Encyclopedia. 2007. Grolier Online. Accessed on October 4, 2007.
 "Caliphate." The Columbia Encyclopedia. The Columbia University Press, 2000. 6590. General OneFile. Gale. DISCUS Remote Patron Access ITWeb. Accessed on October 4, 2007.
 "Caliphate." The Columbia Encyclopedia.
 Unless otherwise noted, the source of the remaining content is Blanchard.
 Emerick, Yahiya. The Complete iIdiot's Guide to Understanding Islam. Indianapolis, Indiana: Alpha,
 Wilkinson, Philip. Islam. London: DK, 2002.