Shī‘a Islam, also Shi‘ite Islam or Shi‘ism (Arabic شيعة šīʿah), is the second largest denomination of the Islamic faith after Sunni Islam. Shias adhere to the teachings of the Prophet Muhammad and the religious guidance of his family (who are referred to as the Ahl al-Bayt) or his descendents known as Shi'a Imams.Prophet Muhammad's bloodline only continues through his beloved daughter Fatima Zahra and son-in-law Ali which alongside the prophets grandsons are the Ahl al-Bayt. Thus, Shi'as consider Prophet Muhammad's descendents as the true source of guidance while considering the first three ruling Sunni caliphs a historic occurrence and not something attached to faith. The singular/adjective form is šīʿī (شيعي.) and refers to a follower of the faction of Imam Ali according to the Shia ideology.

Shia Islam, like Sunni Islam, has at times been divided into many branches; however, only three of these currently have a significant number of followers. The best known and the one with most adherents is the Twelvers (اثنا عشرية iṯnāʿašariyya) which have a large percentage in Iran 90% and Iraq; the others are Ismaili and Zaidiyyah. Alawites and Druzes consider themselves Shias, although this is sometimes disputed by mainstream Shias. The Sufi orders among the Shias are the Alevi, Bektashi, Kubrawiya, Noorbakhshi, Oveyssi, Qizilbashi, Hamadani and Fatimid orders and denominations. Twenty percent of Turkey's population is Alevi while Lebanon and Syria have a large presence of Druze and Alawites.

Etymology
Main article: Shia etymology
"Shia" is the short form of the historic phrase šīʿat ʿAlī (شيعة علي), meaning "the followers of Ali" or "the faction of Ali". Both Shia and Sunni sources trace the term to the years preceding the death of Muhammad; see Shia etymology.

The word "Shia" means "followers; members of party". It can be interpreted in a wider sense than just "followers of Ali", to claim that the Shia Muslims are the followers and believers of (Allah) the Almighty Creator of existence, His Prophets (Guides to Heaven), His Messages and the Ahlul Bayt (The Family of the House of Prophet Mohammad)and the prophet's descendents which are the shi'a Imams Fathered by Ali. The Messenger of Allah (Prophet Mohammad) said to Imam Ali: "Good News to you O Ali! Verily you and your companions and your Shia (followers) will be in Paradise."

Overview
Shia Muslims believe that the descendents from Muhammad through his beloved daughter Fatima Zahra and his son-in-lawAli (the Imams) were the best source of knowledge about the Qur'an and Islam, the most trusted carriers and protectors of Muhammad's Sunnah (traditions), and the most worthy of emulation.

In particular, Shia Muslims recognize the succession of Ali (Muhammad's cousin, son-in-law, the first young man to accept Islam — second only to Muhammad's wife Khadija — the male head of the Ahl al-Bayt or "people of the [Prophet's] house") and the father of the Prophet Muhammad's only bloodline as opposed to that of the caliphate recognized by Sunni Muslims. Shia Muslims believe that Ali was appointed successor by Muhammad's direct order on many occasions, and that he is therefore the rightful leader of the Muslim faith.

This difference between following either the Ahl al-Bayt (Muhammad's family and descendents) or the Caliph Abu Bakr has shaped Shia and non-Shia views on some of the Qur'an, the Hadith (narrations from the prophet) and other areas of Islam. For instance, the collection of Hadith venerated by Shia Muslims is centered around narrations by members of the Ahl al-Bayt, while some Hadith by narrators not belonging to the Ahl al-Bayt are not included (those of Abu Huraira, for example). Ali was the third successor to Abu Bakr and, for the Shia, the first divinely sanctioned "imam," or male descendant of the Prophet Muhammad. The seminal event in Shia history is the martyrdom in 680 CE of Ali's son Hussein, who led an uprising against the "illegitimate" caliph (72 of Hussein's followers were killed as well). For the Shia, Hussein came to symbolize resistance to tyranny.

Regardless of the dispute about the Caliphate, the Shia recognize the religious authority of the Shia Imams, also called Khalifa Ilahi.

Demographics
Some estimates that approximately 15% of the world's Muslims are Shia. There are an estimated 130 to 190 million Shia Muslims[2] (including Twelvers, Ismailis, Zaydis) throughout the world, about three quarters of whom reside in Iran, Pakistan, India, Iraq, Azerbaijan, and Afghanistan. [3][4]

A large portion of the world's Shia live in the Middle East. They constitute a majority in Azerbaijan, Iraq, Bahrain and especially Iran, where 90% of the population is Shia, giving it the highest population of Shia Muslims of any country in the world[3]. In Lebanon Shia form a plurality, and they remain as significant minorities in Afghanistan, Syria, India, Pakistan, Turkey and Yemen. Among the smaller Persian Gulf states, Qatar, Kuwait and the United Arab Emirates also have significant Shia minorities, as does the Eastern Province of Saudi Arabia.

About 20% of India's Muslim population is Shia, and significant Shia communities exist on the coastal regions of West Sumatra and Aceh in Indonesia (see Tabuik). Shia presence is negligible elsewhere in Southeast Asia, where Muslims are predominantly Shafi'i Sunnis.

According to the Shia, one of the lingering problems in estimating the Shia population is that unless the Shia form a significant minority in a Muslim country, the entire population is often listed as Sunni. The reverse, however, has not held true, which may contribute to imprecise estimates of the size of each sect. For example, the 1926 rise of the House of Saud in Arabia brought official discrimination against Shia [5]. The Shia-majority areas of Al-Ahsa, Qatif and Hofuf on the Persian Gulf, and western Arabia provinces of Jazan, Asir and Hijaz, that had large Shia minorities, have officially been completely stripped of their religious identities. Some Shia claim that they endure much bigotry and other indignities from Walmen authorities daily and that Shia pilgrims from other countries are often singled out for harassment (see Status of religious freedom in Saudi Arabia); in Saudi Arabia they are called accaf (عكف) which means rejecters (رافضه).

Doctrines
Main doctrines
The Shia believe in the five pillars of Islam, as do Sunnis, but categorize them differently. Shia beliefs include the following:

Theology of Shia (Usūl al-Dīn)

Tawhīd (Oneness): The Oneness of God
Adalah (Justice): The Justice of God
Nubuwwah (Prophethood): God has appointed perfect and infallible prophets and messengers to teach mankind the religion (that is, a perfect system of how to live in "peace" ("submission to God"))
Imamah (Leadership): God has appointed specific leaders to lead and guide mankind — a prophet appoints a custodian of the religion before his demise
Qiyamah (The Day of Judgment): God will raise mankind for Judgment
Branches of Religion (Furū al-Dīn)

Salat — called "Namaaz" in Persian — (Prayer) – performing the five daily prayers
Sawm — called "Roozeh" in Persian — (Fast) – fasting during the holy month of Ramadhan
Hajj (Pilgrimage) – performing the pilgrimage to Mecca
Zakat (Poor-rate) – paying the poor-tax
Khums (One-fifth of savings) – paying tax to the Imam (سهم اما)
Jihad (Struggle) – struggling to please the almighty. The greater, or internal Jihad is the struggle against the evil within one's soul in every aspect of life. The lesser, or external, Jihad is the struggle against the evil of one's environment in every aspect of life. This is not to be mistaken with the common modern misconception that this means "Holy War". Writing the truth (jihad bil qalam) and speaking truth in front of an oppressor are also forms of Jihad.
Amr-Bil-Ma'rūf – commanding what is good
Nahi-Anil-Munkar – forbidding what is evil
Tawalla – loving the Ahlul Bayt and their followers
Tabarra – dissociating oneself from the enemies of the Ahlul Bayt