Both Sunni Muslims and Shia Muslims agree on the three holiest sites in Islam being, respectively, the Masjid al-Haram (including the Kaaba), in Mecca; the Al-Masjid an-Nabawi, in Medina; and the Al Aqsa Mosque compound, in Jerusalem.
Shia Muslims number 200 million and are the second largest denomination in the faith. Many perform the hajj, and they also travel to Iran, Iraq and beyond to visit holy sites. In Mina, Saudi Arabia, hundreds of Shias have travelled from Britain to perform the hajj.
Mecca is the only pilgrimage site officially accepted by all Muslims, but Iran and Iraq are home to a number of sites considered holy to the Shia faithful: Hussein was buried at Karbala, for example, and the tomb of Ali is in nearby Najaf.
The Saudi government has often been viewed as an active oppressor of Shiites because of the funding of the Wahhabi ideology which denounces the Shiite faith. According to a 2009 Human Rights Watch report, Shiite citizens in Saudi Arabia "face systematic discrimination in religion, education, justice, and employment".
Today Muslims of all branches, including the Sunni and the Shia, all pray towards the Kaaba.
After the four holy cities of Islam (Mecca, Medina, Jerusalem and Damascus, which houses the Umayyad Mosque, often considered the fourth holiest site in Islam), some of the most revered sites by Shias include Cairo, in Egypt, Najaf and Karbala, in Iraq, and Qom and Mashhad, in Iran.
Sunni and Shia Muslims share many central beliefs, including a belief in the Oneness of Allah (tawhid), and that Prophet Muhammad (peace be upon him and his family) was the final Messenger of Allah, who received Divine revelations recorded in the Holy Qur'an.
Sunni and Shi'ite Muslims share the same faith and abide by the same five pillars of Islam (Professor 7 Oct. 2003). There are no rules forcing a woman to adopt her husband's particular branch of Islam (ibid.).
Shias comprise a majority in Iran, Iraq, Azerbaijan, and Bahrain, and a plurality in Lebanon, while Sunnis make up the majority of more than forty countries from Morocco to Indonesia.
The annual rates of growth for the world's Sunni and Shia populations were identical from 1990 to 2000. But the rate of growth of the Shia population is expected to be slightly lower than the rate of growth for Sunnis over the next 20 years.
Eid al-Mubahila, an Eid for Shia Muslims which marks the success of Muslims in a peaceful debate with the Christians of the time. Eid-e-Shuja', an Eid for Shia Muslims which marks the end of the mourning period after the events of Karbala.
The Shī'ah use the same Qur'an as Sunni Muslims, however they do not believe that it was first compiled by Uthman ibn Affan. The Shī'ah believe that the Qur'an was gathered and compiled by Muhammad during his lifetime.
For the most part, Sunnis and Shias observe Ramadan the same way, but there are some differences. For one, Sunnis break their fast at sunset, once the sun is no longer visible, but there is still light in the sky. However, for Shias they wait to break after it gets completely dark.
Shia Ismailis and Ithna'asharis invoke the names of the Prophet and their Imams in prayers and devotional practices to seek help from God. Sometimes, prayers for help or easing of difficulties (mushkil asan) are addressed directly to the Prophet or Imams.
Shiite Muslims include the words and deeds of some of the prophet's family in the Sunna. However, sharia largely comprises the interpretive tradition of Muslim scholars.
The state religion in Qatar is Islam. Most Qataris belong to the Sunni sect of Islam. Shiites comprise around 10% of Qatar's Muslim population. Religious policy is set by the Ministry of Islamic Affairs and Islamic instruction is compulsory for Muslims in all state-sponsored schools.
In a poll conducted by Sabancı University in 2006, 98.3% of Turks revealed they were Muslim. Most Muslims in Turkey are Sunni Muslims forming about 90%, and Shia-Aleviler (Alevis, Ja'faris and Alawites) denominations in total form up to 10% of the Muslim population.
Iran is the world's largest Shiite country whose main Muslim rival is Sunni kingpin Saudi Arabia.
Pakistan is a Sunni majority country, with 76% of Pakistanis identifying as Sunni and 10-15% estimated to be Shi'ites. Both variations of Islam have many different religious schools that Pakistanis adhere to.
In societies that practice polygamy, the specific type is polygyny, which is having more than one wife (polyandrous unions, of having more than one husband, are much less common). Muslim societies allow for up to four wives, but not without specific rules and regulations.
The Shi'ite theologians persisted and nikah mut'ah was legalized for the Twelver Shia during Akbar's reign. According to Sunni Arab jurisdiction of Jordan; if the nikah mut'ah meets all other requirements, it is treated as if it were a permanent marriage.
In Shia Islam, it is permissible under specific circumstances — they argue that the ban came from the second Caliph Umar. If a man is separated from his wife, he may enter into a temporary marriage-contract with another woman with a specified mahr mutually agreed upon.
Sunni Muslims only combine the five daily prayers if they have a good reason to, for example if they are travelling. Shi'a Muslims have more freedom to combine certain prayers, such as the midday and afternoon prayers. Therefore they may only pray three times a day.
For Sunni Muslims, the Shahadah is: There is no God but Allah, and Muhammad is the Prophet of Allah. Shi'a Muslims add an extra phrase to the Shahadah: And Ali is the friend of God. This shows their belief that Ali, Muhammad's cousin, was the true successor to Muhammad.
In some countries in the Middle East and North Africa with predominantly Sunni populations, such as Egypt and Morocco, the prevailing view is that Shias are not members of the Islamic faith. In Iraq and Lebanon, however, overwhelming majorities of all Muslims affirm Shias are Muslims.