Shia Islam (Arabic: شيعة, Shīʿah, singular/adjective form is Shi'i (Arabic: شيعي)) is the second largest denomination of Islam. The followers of Shia Islam are called Shi'ites or Shias. "Shia" is the short form of the historic phrase Shīʻatu ʻAlī (Arabic: شيعة علي), meaning "followers of Ali", "faction of Ali", or "party of Ali".    
Like other schools of thought in Islam, Shia Islam is based on the teachings of the Quran and the message of the Islamic prophet Muhammad.  In contrast to other schools of thought, the Shia believe that only God has the right to choose a representative to safeguard Islam, the Quran and sharia (based upon verses in the Quran which stipulate this according to the Shia). For this reason, the Shias look to Ali, whom they consider divinely appointed, as the rightful successor to Muhammad, and the first imam. The Shia believe that there are numerous narrations where Muhammad selected Ali as his successor. 
Shias believe that Muhammad's family, the Ahl al-Bayt ("the People of the House"), and certain individuals among his descendants, who are known as Imams, have special spiritual and political authority over the community. Therefore, Shias prefer hadiths attributed to the Ahl al-Bayt and close associates, and have their own separate collection of hadiths.  All Shias agree on the succession of Hassan and Hussein after Ali, but they may differ after Hussein.  Hassan and Hussein are described by Shias as "leaders of all youths in Paradise", and believe that these sons of Ali were the true leaders and caliphs of the Muslims.  Shias regard Ali as the successor of Muhammad not only ruling over the community in justice, but also interpreting Islamic practices and its esoteric meaning. Hence he was regarded as being free from error and sin (infallible), and appointed by God by divine decree (nass) to be the first Imam. Ali is known as "perfect man" (al-insan al-kamil) similar to Muhammad, according to Shia viewpoint.
See main article: Shia etymology. The word Shia (Classical Arabic: Arabic: شيعة ) means follower and is the short form of the historic phrase (Arabic: شيعة علي), meaning "followers of Ali", "faction of Ali", or "party of Ali".    The term has widely appeared in hadith and is repeated four times in the Quran; for example verse 37:83 mentions Abraham as a Shia (follower) of Noah. Shi'ite, Shiite, Shia, and Shiism are alternative terms.
The position of Ali is supported by numerous hadith, including Hadith of the pond of Khumm, Hadith of the two weighty things, Hadith of the pen and paper, Hadith of the invitation of the close families, and Hadith of the Twelve Successors. In particular, the Hadith of the Cloak is often quoted to illustrate Muhammad's feeling towards Ali and his family by both Sunni and Shia scholars. Therefore, Shias use hadiths narrated by the Ahl al-Bayt and close associates to understand the Quran.
Although there were several Shia branches through history, modern Shia Islam is divided into three main branches. The largest Shia sect in the early 21st century is the Ithna ashariyya, commonly referred to in English as the Twelvers, while smaller branches include the Ismaili and Zaidi.
The Shia Islamic faith is vast and inclusive of many different groups. Shia theological beliefs, and religious practises such as prayers slightly differ from the Sunnis. While all Muslims pray five times daily, Shias have the option of always combining Dhuhr with Asr and Maghrib with Isha', as there are three distinct times mentioned in the Quran. The Sunnis tend to combine only under certain circumstances.  Shia Islam embodies a completely independent system of religious interpretation and political authority in the Muslim world.  The Shia identity emerged during the lifetime of Muhammad, and Shia theology was formulated in the 2nd century AH, or after Hijra (8th century CE). The first Shia governments and societies were established by the end of the 3rd century AH/9th century CE. The 4th century AH /10th century CE has been referred to by Louis Massignon as 'the Shiite Ismaili century in the history of Islam'.
Twelver Shia Muslims believe that Imam Mahdi (the twelfth imam, Muhammad al-Mahdi) is already on earth and is currently hidden (into occultation, Minor Occultation 874–941, Major Occultation began 941 and is believed to continue until a time decided by Allah) and will return at the end of time, whereas Sunnis believe the Mahdi will appear sometime in the future.
See main article: Shi'a view of Ali.
See also: Hadith of the pond of Khumm, The Farewell Sermon and Eid al-Ghadeer. Shia Muslims believe that just as a prophet is appointed by God alone, only God has the prerogative to appoint the successor to his prophet. Ali was his first caliph. They believe that God chose Ali to be the successor, infallible and divinely chosen. Thus, they say that Muhammad, before his death, appointed Ali as his successor.
Ali was Muhammad's first cousin and closest living male relative as well as his son-in-law, having married his daughter Fatimah.   'Ali would eventually become the fourth Muslim caliph.
Shia Muslims believe that after the last pilgrimage, Muhammad ordered the gathering of Muslims at the pond of Khumm and it was there that Muhammad nominated Ali to be his successor. The hadith of the pond of Khumm (Arabic: '''غدير خم''') refers to the saying (i.e., Hadith) about a historical event of appointment, crucial to Islamic history. This event took place on 18th of Dhu al-Hijjah of 10 AH in the Islamic calendar (March 10, 632 AD) at a place called Ghadir Khumm, which is located near the city of al-Juhfah, Saudi Arabia.
Shia Muslims believe it to be an appointment of Ali by Muhammad as his successor, while Sunni Muslims believe it to be a simple defense of Ali in the face of unjust criticism.
Shia Muslims further believe that the wording of the sermon delivered by Muhammad was as follows:
When Muhammad died, Ali and Muhammad's closest relatives made the funeral arrangements. While they were preparing his body, Abu Bakr, Umar, and Abu Ubaidah ibn al Jarrah (Abu 'Ubayda) met with the leaders of Medina and elected Abu Bakr as khalifa ("caliph"). Ali and his family were dismayed, but accepted the appointment for the sake of unity in the early Muslim community.
It was not until the murder of the third khalifa, Uthman, that the Muslims in Medina invited 'Ali to become the fourth khalifa.
Ali's rule over the early Muslim community was often contested, to the extent that wars were waged against him. As a result, he had to struggle to maintain his power against the groups who broke away after giving him allegiance, or those who wished to take his position. After Ali's murder in 661 CE, his main rival, Muawiyah, claimed the caliphate. While the rebels who accused Uthman of nepotism affirmed Ali's khilafa, they later turned against him and fought him.
Ali ruled from 656 CE to 661 CE, when he was assassinated. while prostrating (sujud) in prayer. Shia add "و عليٌ وليُّ الله" "and Ali is the wali (chosen one) of God" (wa-'Aliyun waliyu l-Lāh), to the adhan and Shahada but this is not obligatory. Ali is regarded as the foremost authority on the Tafsir and hadith.
See main article: Hussein ibn Ali. The Shia regard Hussein ibn Ali as an imam (which is considered a divine spiritual leader appointed by God) and a martyr. He is believed to be the third of the imams from the Ahl al-Bayt, who are supposed to succeed Muhammad, and that he set out on his path in order to save the religion of Islam and the Islamic nation from annihilation at the hands of Yazid I. He is notable for being the last imam following Ali whom all Shia sub-branches agree on.
See main article: Imamah (Shi'a doctrine).
Most of the early Shia as well as Zaydis differed only marginally from mainstream Sunnis in their views on political leadership, but it is possible in this sect to see a refinement of Shia doctrine. Early Sunnis traditionally held that the political leader must come from the tribe of Muhammad—namely, the Quraysh. The Zaydis narrowed the political claims of the Ali's supporters, claiming that not just any descendant of Ali would be eligible to lead the Muslim community (ummah) but only those males directly descended from Muhammad through the union of Ali and Fatimah. But during the Abbasid revolts, other Shia, who came to be known as Imamiyyah (followers of the imams), followed the theological school of Ja'far al-Sadiq. They asserted a more exalted religious role for imams and insisted that, at any given time, whether in power or not, a single male descendant of Ali and Fatimah was the divinely appointed imam and the sole authority, in his time, on all matters of faith and law. To those Shia, love of the imams and of their persecuted cause became as important as belief in God's oneness and the mission of Muhammad.
Later most of Shia, including Twelver and Ismaili, became Imamis. Imami Shia believe that Imams are the spiritual and political successors to Muhammad. Imams are human individuals who not only rule over the community with justice, but also are able to keep and interpret the divine law and its esoteric meaning. The words and deeds of Muhammad and the imams are a guide and model for the community to follow; as a result, they must be free from error and sin, and must be chosen by divine decree, or nass, through Muhammad. 
According to this view, there is always an Imam of the Age, who is the divinely appointed authority on all matters of faith and law in the Muslim community. Ali was the first imam of this line, the rightful successor to Muhammad, followed by male descendants of Muhammad through his daughter Fatimah.
This difference between following either the Ahl al-Bayt (Muhammad's family and descendants) or Caliph Abu Bakr has shaped Shia and non-Shia views on some of the Quran, the hadith (narrations from Muhammad) and other areas of Islam. For instance, the collection of Hadith venerated by Shia Muslims is centered on narrations by members of the Ahl al-Bayt and their supporters, while some Hadith by narrators not belonging to or supporting the Ahl al-Bayt are not included (those of Abu Hurairah, for example). According to Sunnis, Ali was the fourth successor to Abu Bakr, while the Shia maintain that Ali was the first divinely sanctioned "Imam," or successor of Muhammad. The seminal event in Shia history is the martyrdom in 680 CE at the Battle of Karbala of Ali's son Hussein ibn Ali, who led a non-allegiance movement against the defiant caliph (71 of Hussein's followers were killed as well). Hussein came to symbolize resistance to tyranny.
It is believed in Twelver and Ismaili Shia Islam that 'aql, divine wisdom, was the source of the souls of the prophets and imams and gave them esoteric knowledge called ḥikmah and that their sufferings were a means of divine grace to their devotees.   Although the Imam was not the recipient of a divine revelation, he had a close relationship with God, through which God guides him, and the imam in turn guides the people. Imamate, or belief in the divine guide, is a fundamental belief in the Twelver and Ismaili Shia branches and is based on the concept that God would not leave humanity without access to divine guidance.
In Shia Islam, there is a third phrase of the Shahada, Ali-un-waliullah, which depicts the importance of the Imamate.
- The fundamental first phrase La- ilaha-ill-al-lah is the foundation stone of Islam, the belief that "there is no god but Allah". This is the confession of Tawhid.
- According to Shia Islam, Muhammad declared Ali bin Abu Talib as his successor and said that "for whoever I am a Moula of them, Ali is his Moula". Hence, they say the Kalema required further confession of the third phrase Ali-un- wali-ul-lah, meaning "Ali is his (Muhammad's) Wali", its caretaker, stressing the need that for continuation of faith there is a requirement of Wali, the imams who are the real caretakers of Islam.
The Shahada thus includes three Islamic teachings, Tawhid, Nabuwat and Imamate. In this belief, the Nabi, Muhammad and the imams are so linked together that these cannot be viewed separately. One leads to the other and finally to God, "God", the Almighty.
In one of the Qibla of Ma'ad al-Mustansir Billah of the Fatimid Caliphate, the Mosque of Ibn Tulun, was engraved his name and the phrase kalema‐tut‐sahadat (see image above left), giving specific importance to the third phrase, Ali –un‐ wali ‐ ul –lah, hence to the Imamate.
See main article: Ismah. Ismah is the concept of infallibility or "divinely bestowed freedom from error and sin" in Islam. Muslims believe that Muhammad and other prophets in Islam possessed ismah. Twelver and Ismaili Shia Muslims also attribute the quality to Imams as well as to Fatimah, daughter of Muhammad, in contrast to the Zaidi, who do not attribute 'ismah to the Imams.
According to Shia theologians, infallibility is considered a rational necessary precondition for spiritual and religious guidance. They argue that since God has commanded absolute obedience from these figures they must only order that which is right. The state of infallibility is based on the Shia interpretation of the verse of purification. Thus, they are the most pure ones, the only immaculate ones preserved from, and immune to, all uncleanness. It does not mean that supernatural powers prevent them from committing a sin, but due to the fact that they have an absolute belief in God, that they find themselves in the presence of God.
They also have a complete knowledge of God's will. They are in possession of all knowledge brought by the angels to the prophets (nabi) and the messengers (Rasul). Their knowledge encompasses the totality of all times. They thus act without fault in religious matters.
See main article: Tawassul.
Tawassul (Arabic: توسل) is an Islamic religious practice in which a Muslim seeks nearness to God. A rough translation would be: "To draw near to what one seeks after and to approach that which one desires." The exact definition and method of tawassul is a matter of some dispute within the Muslim community.
Muslims who practice tawassul point to the Quran, Islam's holy book, as the origin of the practice. Many Muslims believe it is a commandment upon them to "draw near" to God. Amongst Sufi and Barelvi Muslims within Sunni Islam, as well as Twelver Shia Muslims, it refers to the act of supplicating to God through a prophet, imam or Sufi saint, whether dead or alive.
See main article: The Occultation. The Occultation in Shia Islam refers to a belief that the messianic figure, the Mahdi, is an Imam who has disappeared and will one day return alongside Jesus and fill the world with justice. According to the Twelver Shia, the main goal of the Mahdi will be to establish an Islamic state and to apply Islamic laws that were revealed to the Prophet of Islam. Some Shia, such as the Zaidi and Nizari Ismaili, do not believe in the idea of the Occultation. The groups which do believe in it differ upon which lineage of the Imamate is valid, and therefore which individual has gone into occultation. They believe there are many signs that will indicate the time of his return.
See main article: History of Shi'a Islam.
According to Encyclopædia Britannica and others, the Shia are believed to have started as a political party and developed into a religious movement, influencing Sunnis and producing a number of important sects.
Hossein Nasr disagrees with this and writes:
Western scholarship that views Shi'ism as a political movement is factually incorrect. The concept of separation of church and state did not yet exist in the Muslim community in the 6th century AD. S.H.M Jafri, the author of The Origin and Early Development of Shi'a Islam, writes:
Disagreement broke out over who would succeed Muhammad as leader of the Muslim community. While the Sunnis followed the companions of Muhammad, the Shia followed Ali. This dispute eventually led to the First Fitna, which was the first major civil war within the Islamic Caliphate. The Fitna began as a series of revolts fought against the first Imam, Ali ibn Abi Talib, caused by the assassination of his political predecessor, Uthman ibn Affan. It lasted for the entirety of Ali's reign, and its end is marked by Muawiyah's assumption of the caliphate (founding the Umayyad dynasty), and the subsequent recorded peace treaty between him and Hasan ibn Ali.The Second Fitna was when the first Umayyad Caliph Muawiya I was succeeded upon his death in 680 by his son, Yazid I. Yazid's first opposition came from supporters of Hussein ibn Ali, who was the grandson of Muhammad and the son of the former Caliph Ali ibn Abi Talib, who had been assassinated. Husayn and many of his closest supporters were martyrd by Yazid's troops at the Battle of Karbala. This battle is often cited as the definitive break between the Shia and Sunni sects of Islam, and until this day it has been commemorated each year by Shia Muslims on the Day of Ashura.
See main article: Fatimid Caliphate. One of the earliest nations where the rulers were Shia (Ismaili) Muslims was the Fatamid Caliphate, which controlled much of North Africa, the Levant, parts of Arabia and Mecca and Medina.
A major turning point in Shia history was the Safavid dynasty in Persia.
With the fall of the Safavids, the state in Persia – including the state system of courts with government-appointed judges (qadis) – became much weaker. This gave the Sharia courts of mujtahids an opportunity to fill in the slack and enabled "the ulama to assert their judicial authority." The Usuli School also increased in strength at this time.
The Akhbari movement "crystalized" as a "separate movement" with the writings of Muhammad Amin al-Astarabadi (died 1627 AD). It rejected the use of reasoning in deriving verdicts and believed that only the Quran, hadith, (prophetic sayings and recorded opinions of the Imams) and consensus should be used as sources to derive verdicts (fatāwā). Unlike Usulis, Akhbari did and do not follow marjas who practice ijtihad.
It achieved its greatest influence in the late Safavid and early post-Safavid era, when it dominated Twelver Shia Islam. However, shortly thereafter Muhammad Baqir Behbahani (died 1792), along with other Usuli mujtahids, crushed the Akhbari movement. It remains only a small minority in the Shia Muslim world. One result of the resolution of this conflict was the rise in importance of the concept of ijtihad and the position of the mujtahid (as opposed to other ulama) in the 18th and early 19th centuries. It was from this time that the division of the Shia world into mujtahid (those who could follow their own independent judgment) and muqallid (those who had to follow the rulings of a mujtahid) took place. According to author Moojan Momen, "up to the middle of the 19th century there were very few mujtahids (three or four) anywhere at any one time," but "several hundred existed by the end of the 19th century."
Muhammad Baqir Majlisi, commonly referenced to using the title Allamah, was a highly influential scholar during the 17th century (Safavid era). Majlisi's works emphasized his desire to purge Twelver Shi`ism of the influences of mysticism and philosophy, and to propagate an ideal of strict adherence to the Islamic law (sharia). Majlisi promoted specifically Shia rituals such as mourning for Hussein ibn Ali and visitation (ziyarat) of the tombs of the Imams and Imamzadas, stressing "the concept of the Imams as mediators and intercessors for man with God."
See main article: List of countries by Muslim population.
They may number up to 200 million as of 2009. The Shia majority countries are Iran, Iraq, Azerbaijan and Bahrain. They also constitute 36.3% of entire local population and 38.6% of the local Muslim population of the Middle East.
Shia Muslims constitute over 35% of the population in Lebanon, over 45% of the population in Yemen, 20-40% of the population in Kuwait , over 20% in Turkey, 10–20% of the population in Pakistan, and 10-19% of Afghanistan's population. 
Saudi Arabia hosts a number of distinct Shia communities, including the Twelver Baharna in the Eastern Province, the Nakhawila of Medina, and the Ismaili Sulaymani and Zaidiyyah of Najran. Estimations put the number of Shiite citizens at 2-4 million, accounting for roughly 15% of the local population.
Significant Shia communities exist in the coastal regions of West Sumatra and Aceh in Indonesia (see Tabuik). The Shia presence is negligible elsewhere in Southeast Asia, where Muslims are predominantly Shafi'i Sunnis.
A significant Shia minority is present in Nigeria, centered around Kano State (see Shi'a Islam in Nigeria). East Africa holds several populations of Ismaili Shia, primarily descendants of immigrants from South Asia during the colonial period, such as the Khoja.
According to Shia Muslims, one of the lingering problems in estimating Shia population is that unless 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.
|Country||Shia population <||-- This column shows Pew statistics only, please!-->||Percent of Muslim population that is Shia <||-- This column shows Pew statistics only, please!-->||Percent of global Shia population <||-- This column shows Pew statistics only, please!-->||Minimum estimate/claim <||-- Plz provide reliable, verifiable web-reference with the claim -->||Maximum estimate/claim <||-- Plz provide reliable, verifiable web-reference with the claim -->|
|Iran||66,000,000 – 70,000,000||90–95||37–40|
|Pakistan||48,000,000 – 53,000,000||22–27||22–27||43,250,000 – 57,666,666 |
|India||16,000,000 – 24,000,000||10–15||9–14||40,000,000 – 50,000,000.|
|Indonesia||5,000,000 – 6,000,000||2.7||3||<7,000,000|
|Iraq||19,000,000 – 22,000,000||65–70||11–12|
|Turkey||7,000,000 – 11,000,000||10–15||4–6|
|Yemen||8,000,000 – 10,000,000||35–40||5|
|Azerbaijan||5,000,000 – 7,000,000||65–75||3–4||85% of total population|
|Afghanistan||3,000,000 – 4,000,000||10–15||<2||15–19% of total population|
|Syria||3,000,000 – 4,000,000||15–20||<2|
|Saudi Arabia||3,000,000 – 4,000,000||15–22||<1|
|Lebanon||1,000,000 – 1,600,000||30-35  ||<1||Estimated, no official census.|
|Oman||700,000 – 900,000||5–10||<1||948,750|
|Kuwait||500,000 – 700,000||30–35||<1||35–40% of total population|
|Germany||400,000 – 600,000||10–15||<1|
|Bahrain||375,000 – 400,000||66–70||<1||375,000 (66% of citizen population)||400,000 (70% of citizen population)|
|United Arab Emirates||300,000 – 400,000||10||<1|
|United States||200,000 – 400,000||10–15||<1|
|United Kingdom||100,000 – 300,000||10–15||<1|
The dispute over the right successor to Muhammad resulted in the formation of two main sects, the Sunni and the Shia. The Sunni, or "followers of the way," followed the caliphate and maintained the premise that any devout Muslim could potentially become the successor to Muhammad if accepted by his peers. The Shia, however, maintain that only the person selected by God and announced by the Prophet could become his successor; thus, Ali became the religious authority for the Shia people. Militarily established and holding control over the Umayyad government, many Sunni rulers perceived the Shia as a threat – both to their political and religious authority.
The Sunni rulers under the Umayyads sought to marginalize the Shia minority, and later the Abbasids turned on their Shia allies and imprisoned, persecuted, and killed them. The persecution of the Shia throughout history by Sunni co-religionists has often been characterized by brutal and genocidal acts. Comprising only about 10–15% of the entire Muslim population, the Shia remain a marginalized community to this day in many Sunni Arab dominant countries without the rights to practice their religion and organize.
At various times Shia groups have faced persecution.     In 1514 the Ottoman sultan, Selim I, ordered the massacre of 40,000 Anatolian Shia. According to Jalal Al-e-Ahmad, "Sultan Selim I carried things so far that he announced that the killing of one Shiite had as much otherworldly reward as killing 70 Christians." In 1801 the Al Saud-Wahhabi armies attacked and sacked Karbala, the Shia shrine in eastern Iraq that commemorates the death of Husayn.
In March 2011, the Malaysian government declared the Shia a 'deviant' sect and banned them from promoting their faith to other Muslims, but left them free to practise it themselves.
See main article: Shia days of remembrance.
Both Sunni and Shia, celebrate the following annual holidays:
The following days are some of the most important holidays observed by Shia Muslims:
See main article: Holiest sites in Islam (Shia).
Additionally, other venerated sites include Wadi-us-Salaam cemetery in Najaf, Al-Baqi' cemetery in Medina, Imam Reza shrine in Mashhad, Kadhimiya Mosque in Kadhimiya, Al-Askari Mosque in Samarra, Sahla Mosque and Great Mosque of Kufa in Kufa and several other sites in the cities of Qom, Susa and Damascus.
Most of the holy Islamic sites in today's Saudi Arabia have been destroyed by Wahhabis and the Saudi royal family, the most notable being the shrines and tombs in the Al-Baqi' cemetery in 1925. In 2006, a bombing resulted in the destruction of the shrine of Al-Askari Mosque.
The Shia faith throughout its history split over the issue of the Imamate. The largest branch are the Twelvers, followed by the Zaidi and Ismaili. All three groups follow a different line of Imamate.
See main article: Twelver and Criticism of Twelver Shi'ism. Twelver Shia or the Ithnā'ashariyyah' is the largest branch of Shia Islam, and the term Shia Muslim usually refers to Twelver Shia Muslims only. The term Twelver is derived from the doctrine of believing in twelve divinely ordained leaders, known as The Twelve Imams. Twelver Shia are also known as Imami or Ja'fari, originated from the name of the 6th Imam, Ja'far al-Sadiq, who elaborated the twelver jurisprudence.
More specifically, these principles are known as Usul al-Madhhab (principles of the Shia sect) according to Twelver Shias which differ from Daruriyat al-Din (Necessities of Religion) which are principles in order for one to be a Muslim. The Necessities of Religion do not include Leadership (Imamah) as it is not a requirement in order for one to be recognized as a Muslim. However, this category, according to Twelver scholars like Ayatollah al-Khoei, does include belief in God, Prophethood, the Day of Resurrection and other "necessities" (like belief in angels). In this regard, Twelver Shias draw a distinction in terms of believing in the main principles of Islam on the one hand, and specifically Shia doctrines like Imamah on the other.
See also: The Twelve Imams and Hadith of the Twelve Successors. The Twelve Imams are the spiritual and political successors to Muhammad for the Twelvers. According to the theology of Twelvers, the successor of Muhammad is an infallible human individual who not only rules over the community with justice but also is able to keep and interpret the divine law and its esoteric meaning. The words and deeds of Muhammad and the imams are a guide and model for the community to follow; as a result, they must be free from error and sin, and Imams must be chosen by divine decree, or nass, through Muhammad.  Each Imam was the son of the previous Imam, with the exception of Hussein ibn Ali, who was the brother of Hasan ibn Ali. The twelfth and final Imam is Muhammad al-Mahdi, who is believed by the Twelvers to be currently alive and in occultation.
|1st||Ali||600 - 661||ʿAlī ibn Abī Ṭālib , also known as Amīr al-Muʾminīn|
|2nd||Hasan ibn Ali||625 – 669||Ḥasan ibn ʿAlī , also known as al-Ḥasan al-Mujtaba|
|3rd||Hussein ibn Ali||626 – 680||Ḥusayn ibn ʿAlī , also known as al-Ḥusayn al-Shahīd|
|4th||Zayn al-‘Ābidīn||658 – 713||ʿAlī ibn al-Ḥusayn , also known as ʿAli Zayn al-ʿAbidīn|
|5th||Muhammad al-Baqir||676 – 743||Muḥammad ibn ʿAlī , also known as Muḥammad al-Bāqir|
|6th||Ja'far al-Sadiq||703 – 765||Jaʿfar ibn Muḥammad , also known as Jaʿfar al-Ṣādiq|
|7th||Musa al-Kazim||745 – 799||Mūsā ibn Jaʿfar , also known as Mūsā al-Kāẓim|
|8th||Ali al-Rida||765 – 818||ʿAlī ibn Mūsā , also known as ʿAli al-Riḍā|
|9th||Muhammad al-Taqi||810 – 835||Muḥammad ibn ʿAlī , also known as Muḥammad al-Jawād and Muḥammad al-Taqī|
|10th||Ali al-Hadi||827 – 868||ʿAlī ibn Muḥammad , also known as ʿAlī al-Hādī and ʿAlī al-Naqī|
|11th||Hasan al-Askari||846 – 874||Ḥasan ibn ʿAlī , also known as Ḥasan al-ʿAskarī|
|12th||Muhammad al-Mahdi||869 – In occultation||Muḥammad ibn al-Ḥasan , also known as al-Ḥujjat ibn al-Ḥasan, Imam al-Mahdī, Imam al-Aṣr, al-Qāʾim, etc.|
See main article: Ja'fari jurisprudence.
See also: Shi'a clergy. The Twelver jurisprudence is called Ja'fari jurisprudence. In this jurisprudence Sunnah is considered to be the oral traditions of Muhammad and their implementation and interpretation by the twelve Imams. There are three schools of Ja'fari jurisprudence: Usuli, Akhbari, and Shaykhi. The Usuli school is by far the largest of the three. Twelver groups that do not follow Ja'fari jurisprudence include the Alawi, Alevi, Bektashi, and Qizilbash.
In Ja'fari jurisprudence, there are ten ancillary pillars, known as Furu' ad-Din, which are as follows:
According to Twelvers, defining and interpretation of Islamic jurisprudence is the responsibility of Muhammad and the twelve Imams. As the 12th Imam is in occultation, it is the duty of clerics to refer to the Islamic literature such as the Quran and hadith and identify legal decisions within the confines of Islamic law to provide means to deal with current issues from an Islamic perspective. In other words, Twelver clerics provide Guardianship of the Islamic Jurisprudence, which was defined by Muhammad and his twelve successors. This process is known as Ijtihad and the clerics are known as Marja, meaning reference. The labels Allamah and Ayatollah are in use for Twelver clerics.
See main article: Ismailism. The Ismaili are the second largest part of the Shia community after the Twelvers. They get their name from their acceptance of Isma'il ibn Jafar as the divinely appointed spiritual successor (Imam) to Ja'far al-Sadiq, wherein they differ from the Twelvers, who accept Musa al-Kadhim, younger brother of Isma'il, as the true Imam.
After the death or Occultation of Muhammad ibn Ismaill in the 8th century, the teachings of Ismailism further transformed into the belief system as it is known today, with an explicit concentration on the deeper, esoteric meaning (bāṭin) of the faith. With the eventual development of Twelverism into the more literalistic (zahir) oriented Akhbari and later Usuli schools of thought, Shiaism developed in two separate directions: the metaphorical Ismailli group focusing on the mystical path and nature of God and the divine manifestation in the personage of the "Imam of the Time" as the "Face of God", with the more literalistic Twelver group focusing on divine law (sharī'ah) and the deeds and sayings (sunnah) of Muhammad and his successors (the Ahlu l-Bayt), who as A'immah were guides and a light to God.
Though there are several sub-groupings within the Ismailis, the term in today's vernacular generally refers to the Nizari community, who are followers of the Aga Khan and the largest group among the Ismailiyyah. Another famous community which falls under the Isma'il's are the Dawoodi Bohras, whose religious leader is Syedna Mohammed Burhanuddin. While there are many other branches with extremely differing exterior practices, much of the spiritual theology has remained the same since the days of the faith's early Imams. In recent centuries Ismailis have largely been an Indo-Iranian community, but they are found in India, Pakistan, Syria, Palestine, Saudi Arabia, Yemen, China, Jordan, Uzbekistan, Tajikistan, Afghanistan, East Africa and South Africa, and have in recent years emigrated to Europe, Australia, New Zealand, and North America.
See main article: List of Ismaili imams. After the death of Isma'il ibn Jafar, many Ismailis believed the line of Imamate ended and that one day the messianic Mahdi, whom they believed to be Muhammad ibn Ismail, would return and establish an age of justice. One group included the violent Qarmatians, who had a stronghold in Bahrain. In contrast, some Ismailis believed the Imamate did continue, and that the Imams were in occultation and still communicated and taught their followers through a network of dawah "Missionaries".
In 909, Ubayd Allah al-Mahdi Billah, a claimant to the Ismaili Imamate, established the Fatimid Caliphate. During this period, three lineages of imams formed. The first branch, known today as the Druze, began with Al-Hakim bi-Amr Allah. Born in 386 AH (985), he ascended as ruler at the age of eleven. The typical religiously tolerant Fatimid Empire saw much persecution under his reign. When in 411 AH (1021) his mule returned without him, soaked in blood, a religious group that was forming in his lifetime broke off from mainstream Ismailism and did not acknowledge his successor. Later to be known as the Druze, they believe al-Hakim to be the incarnation of God and the prophesied Mahdi who would one day return and bring justice to the world. The faith further split from Ismailism as it developed very unusual doctrines which often class it separately from both Ismailiyyah and Islam.
The second split occurred following the death of Ma'ad al-Mustansir Billah in 487 AH (1094). His rule was the longest of any caliph in any Islamic empire. Upon his passing away, his sons, Nizar the older, and Al-Musta'li, the younger, fought for political and spiritual control of the dynasty. Nizar was defeated and jailed, but according to Nizari tradition, his son escaped to Alamut, where the Iranian Ismaili had accepted his claim. From here on, the Nizari Ismaili community has continued with a present, living Imam.
The Mustaali line split again between the Taiyabi (Dawoodi Bohra is its main branch) and the Hafizi, the former claiming that At-Tayyib Abi l-Qasim (son of Al-Amir bi-Ahkami l-Lah) and the imams following him went into a period of anonymity (Dawr-e-Satr) and appointed a Da'i al-Mutlaq to guide the community, in a similar manner as the Ismaili had lived after the death of Muhammad ibn Ismail. The latter (Hafizi) claimed that the ruling Fatimid Caliph was the Imam, and they died out with the fall of the Fatimid Empire.
Ismailis have categorized their practices which are known as seven pillars. They are as follow:
For Nizaris, there has been importance placed on a scholarly institution because of the existence of a present Imam. The Imam of the Age defines the jurisprudence, and his guidance may differ with Imams previous to him because of different times and circumstances. For Nizari Ismailis, the Imam is His Highness Karim al-Husayni Aga Khan IV. The Nizari line of Imams has continued to this day as an unending line.
Divine leadership has continued in the Bohra branch through the institution of the "Unrestricted Missionary" Dai. According to Bohra tradition, before the last Imam, At-Tayyib Abi l-Qasim, went into seclusion, his father, the 20th Imam Al-Amir bi-Ahkami l-Lah, had instructed Al-Hurra Al-Malika the Malika (Queen consort) in Yemen to appoint a vicegerent after the seclusion – the Unrestricted Missionary, who as the Imam's vicegerent has full authority to govern the community in all matters both spiritual and temporal while the lineage of Mustaali-Tayyibi Imams remains in seclusion (Dawr-e-Satr). The three branches of the Mustaali, the Alavi Bohra, Sulaimani Bohra and Dawoodi Bohra, differ on who the current Unrestricted Missionary is.
See main article: Zaidiyyah. Zaidiyya, Zaidism or Zaydi is a Shia school named after Zayd ibn Ali. Followers of the Zaidi fiqh are called Zaidis (or occasionally Fivers). However, there is also a group called Zaidi Wasītīs who are Twelvers (see below). Zaidis constitute roughly 40–45% of the population of Yemen.
The Zaydis, Twelvers and Ismailis recognize the same first four Imams; however, the Zaidis recognise Zayd ibn Ali as the fifth. After the time of Zayd ibn Ali, the Zaidis recognized that any descendant of Hasan ibn Ali or Hussein ibn Ali could be Imam after fulfilling certain conditions. Other well-known Zaidi Imams in history were Yahya ibn Zayd, Muhammad al-Nafs az-Zakiyah and Ibrahim ibn Abdullah. In matters of Islamic jurisprudence, the Zaydis follow Zayd ibn Ali's teachings which are documented in his book Majmu'l Fiqh (in Arabic: مجموع الفِقه). Al-Hadi ila'l-Haqq Yahya, founder of the Zaydi state in Yemen, instituted elements of the jurisprudential tradition of the Sunni Muslim jurist Abū Ḥanīfa, and as a result, Zaydi jurisprudence today continues somewhat parallel to that of the Hanafis.
The Zaidi doctrine of Imamah does not presuppose the infallibility of the Imam nor that the Imams receive divine guidance. Zaidis also do not believe that the Imamate must pass from father to son but believe it can be held by any Sayyid descended from either Hasan ibn Ali or Hussein ibn Ali (as was the case after the death of Hasan ibn Ali). Historically, Zaidis held that Zayd was the rightful successor of the 4th Imam since he led a rebellion against the Umayyads in protest of their tyranny and corruption. Muhammad al-Baqir did not engage in political action, and the followers of Zayd believed that a true Imam must fight against corrupt rulers.
A Zaydi state was established in Gilan, Deylaman and Tabaristan (northern Iran) in 864 C.E. by the Alavids; it lasted until the death of its leader at the hand of the Samanids in 928 C.E. Roughly forty years later the state was revived in Gilan and survived under Hasanid leaders until 1126 C.E. Afterwards, from the 12th to 13th centuries, the Zaydis of Deylaman, Gilan and Tabaristan then acknowledged the Zaydi Imams of Yemen or rival Zaydi Imams within Iran.
The Buyids were initially Zaidi as well as the Banu Ukhaidhir rulers of al-Yamama in the 9th and 10th centuries. The leader of the Zaydi community took the title of Caliph. As such, the ruler of Yemen was known as the Caliph, al-Hadi Yahya bin al-Hussain bin al-Qasim ar-Rassi Rassids (a descendant of Hasan ibn Ali the son of Ali) who, at Sa'dah, in 893-7 CE, founded the Zaydi Imamate, and this system continued until the middle of the 20th century, when the revolution of 1962 CE deposed the Zaydi Imam. The founding Zaidism of Yemen was of the Jarudiyya group; however, with increasing interaction with Hanafi and Shafi'i rites of Sunni Islam, there was a shift from the Jarudiyya group to the Sulaimaniyya, Tabiriyya, Butriyya or Salihiyya groups. Zaidis form the second dominant religious group in Yemen. Currently, they constitute about 40–45% of the population in Yemen. Ja'faris and Isma'ilis are 2–5%. In Saudi Arabia, it is estimated that there are over 1 million Zaydis (primarily in the western provinces).
Currently the most prominent Zaydi movement is Houthis movement, known by the name of Shabab Al Mu'mineen (Believing Youth). They have been the subject of an ongoing campaign against them by the Yemeni Government in which the army has lost 743 men, and thousands of innocent civilians have been killed or displaced by government forces causing a grave humanitarian crisis in north Yemen.