Consider the following question and answer in society:
Individual A: “Who can I marry?” Culture: “Only one person, and more than likely, that person will be a lot like you.”
There are several societal concepts that help to explain this answer, and break down the overall concept of marriage.
Endogamy is a marriage norm requiring a person to marry someone from inside his or her group, which can be any kind of group.
EXAMPLE
You might have an endogamous marriage with respect to religion or class, meaning you can only marry somebody in the same religion or class.A similar term to endogamy is homogamy. Homogamy is a marriage between two people who are culturally and socially similar. This term sounds a lot like endogamy and is related, but it's not the same thing.
Homogamy differs because it refers to marriages where people voluntarily marry someone who is similar. Sociologists have found that people tend to want to marry somebody who is similar in terms of race, class, age, interests, hobbies, etc., which is homogamy.
The following are examples of homogamous relationships. Note, two people could be of the same age and therefore homogamous, but they might be different races or classes, so are therefore not homogamous along those lines.
What about the opposite, marrying somebody who is different? That is called exogamy, ‘ex’ meaning outside. Exogamy is a marriage between people who belong to different social categories.
EXAMPLE
In some places in India, people must marry somebody from a different village for cultural reasons. This is an exogamous restriction on marriage.Exogamy, having to marry outside, is historically more common in smaller, land-based societies, because you need to put some kind of restriction on marriage so that people ensure they marry outside of the gene pool. If you continually marry and have children within the gene pool in a small population, this can create problems, so cultural sanctions on exogamy developed.
A second question you might have is not just who can you marry, but how many people can you marry? Can you marry five people if you want to? You can marry five people, culture says, but you can't do it at the same time. You have to get married, then get a divorce, then you can get married again, and so on. In American society, a marriage between two people is called monogamy. It's not legal to have more than one wife or husband at a time.
On the hand, marriage to multiple people at the same time is called polygamy. There are two types of polygamy:
Polygamy does happen in society. You can likely think of people you know who have had multiple partners at the same time, but this is not legal within marriage.
EXAMPLE
Hugh Hefner, of Playboy fame, has had many female partners in his life, yet he's not been married to them all at the same time. To obtain the legal designation of marriage, you have to be in a monogamous relationship.Source: This work is adapted from Sophia author Zach Lamb.