Nikah mut'ah

In some forms of the religion Islam, Nikah mut'ah is a form of marriage. It is also called Sigheh. Unlike Nikāḥ, which is the other form of marriage in Islamic law, a Nikah mut'ah marriage does not last for the two people's whole lives. It lasts only limited time. Nikah mutah is about sexual pleasure. The Twelver Shia Muslims say that Nikah mut'ah is legal, but most other Muslims disagree. 
Conditions.
Some things must be true for a Nikah mut'ah:
Nikah mut'ah is different from the other form of marriage in other ways too:
Nikah mut'ah does not have to be publicly announced. Islam says that Muslim men may have only four and no more, but this only applies to Nikah-marriages.
According to Ayatollah Ali al-Sistani, the Nikah mut'ah is the only way a Muslim can marry a person of the Book who is not Muslim. He says Nikah is not possible with non-Muslims. Other Ayatollahs say that Muslims can marry non-Muslim people of the book.
Criticism.
Nikah mut'ah has been used to cover child prostitution. Some Western writers have argued that mut'ah is similar to prostitution. Julie Parshall writes that mut'ah is legalised prostitution allowed by the Twelver Shia authorities. She quotes the Oxford encyclopedia of modern Islamic world to make a difference between marriage (nikah) and mut'ah. She also says that while nikah is for having children, mut'ah is just for sexual gratification.