I want to know about marriage in Islam.

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions. There are two types of marriage in Islam. First, the valid marriage, which is the one that fulfils all the conditions set by Islamic Shariah. Second, the invalid marriage; this has many kinds: 1) Muta'a (temporary marriage). 2) Tahleel marriage (marriage to a woman to make her lawful for her husband who had divorced thrice). 3) Al Shighar marriage. 4) Any marriage act that falls short of fulfilling any of the conditions of a valid marriage. Details about marriages are abundant in Fiqh books and there are some Fatawa in the web about this subject. Allah knows best.