The majority of the population of Iran follows the "Shia" beliefs of Islam. Most Iranians follow the primary branch of Shia Islam called "Ithna Ashariyyah" (or "Twelvers" in English). Iran's Shia population constitutes almost 90-95% of its Muslim population and almost 40% of the entire world's Shia population.
"Sunni" Islam is the other major branch of Islam. Majority of the world's Muslims are Sunnis and they constitute between 80-90% of the global Muslim population. Shias believe that Ali, who was Prophet Mohammed's first cousin and son-in-law was his true successor, whereas Sunni's believe that after Prophet Mohammed, the first four Caliphs were his rightful successors.
The institution of Shia marriage involves Pillars ( "A rkan") and "Statutes" ( "A hkam"). The pillars of marriage are "Sigha" (Formula) and "Mahall" (Persons). Other branches of Islam have additional pillars regarding Guardianship and Witnesses, but these are not entirely applicable to Shia marriages.
The "Sigha" (Formula) states that marriage is a legalized contract ( " 'aqd"). There is a declaration ( "ijab" ) by the woman that she proposes to get married to a man and acceptance ( "qabul") by the man to take her as his wife.
The "Mahall" (Persons) lays down rules when a woman and man can not marry. Marriage is not allowed between a Muslim woman and a non-Muslim man, with blood relatives, with relations by marriage, with two sisters, with a foster mother who wet nurses a child, if the man already has four wives, if the man and woman have been previously divorced and the woman has not remarried and divorced.
Marriage statutes include Dower ( "Mahr" ), Support ( "Nafaqa") and Annulment ( "Faskh"). The Dower / Dowry can be in the form of cash, property or other assets that belong to the husband. The Dower is given to the wife at the time of the marriage. Support indicates how the wife is treated (including food, clothes, shelter, etc) once she lives with her husband. Annulment relates to the annulment of the marriage in case of a disability. Disabilities can be mental or physical and can include insanity, impotence, leprosy, etc.
Shias allow a form of temporary marriage called "Nikah Mut'ah". The duration of the marriage is fixed at the start of the marriage and the marriage gets annulled at the end of the period. This form of temporary marriage ( "Mut'ah ") is mainly observed in Iran. There are four pillars of a Mut'ah ( sourced from Murata (1987)); the first two, "Formula" and "Persons", are similar to a permanent marriage. The third pillar is "Duration" ( "Mudda") and the fourth pillar is "Dower". The Mut'ah must have a stipulated time period with a date on which it will be annulled and it must have a Dower / Dowry.
Most Islamic countries do not recognize temporary marriages. Most Western countries not only do not recognizetemporary marriages, they also do not recognize polygamy. Consider the case of an Iranian family that wants to immigrate to the USA. If there is more than one wife in the family, the man of the family will be able to take only one wife and will have to show to the US authorities that he has divorced his other wives. What complicates matters further is that diplomatic ties between Iran and USA are practically non-existent. Since the US does not have an embassy in Iran, Iranian applicants who want to immigrate to the US have to travel to Switzerland or UAE or Turkey. Furthermore, Iranian legal – documents, color : such color : as Marriage / divorce certificates, academic records, etc are On in Farsi and the applicant has to Provide Farsi certified translations for these documents.