The institution of marriage predates recorded human history, therefore, it becomes impossible to ascertain who initiated or put forward the idea of marriage for the first time. The oldest historical record, which dictates marriage laws dates back to the Mesopotamians. These laws are to be found in the tablet called Codex Hammurabi (code of Hammurabi).
Cultures around the world have their own theories on why this institution was brought into place. Evolutionists say the need for survival played a big role. They argue the childhood of a human is the longest in the animal kingdom. It typically lasts for 15 to 18 years. And a child is vulnerable if there is no one to protect him/her in this period. This was the main reason, they say, behind marriages coming into being. Other theories suggest the concept was born to moderate the competition between men for access to women.
Today, there are well-established systems around the world which control this institution. And marriages, depending upon the sexes and number of persons involved are further divided into the following categories:
Heterosexual marriages: These are the most common of all marriages and almost every country in the world recognizes them. A man and a woman may tie up in these kinds of marriages.
Homosexual marriages: As the name suggests, in this case, both the husband and the wife belong to the same sex. These marriages are illegal in many nations.
Polygamous marriages: If a man has more than one wife then he is said to be polygamous and the marriages done by him would be polygamous marriages.
Polygyny marriages: In this case a woman has more than one husband.
Then they can be further sub-divided into whether one is marrying one into his/her social group or not etc.