Polygamy and Polyandry

In relation with other people or in the societies, we often find the form of marriage called monogamy. Monogamy actually is the form of marriage practiced in the western world. All states have legal prohibitions against a man having more than one wife and a woman having more than one husband, and the penalties for polygamy (having more than one spouse at a time) can be quite severe.

Polygamy is the marriage of a person of either sex to more than one spouse. Polyandry, another form of polygamy, is the marriage of one woman to more than one man.

Do you have opinions about certain form of marriage mentioned above ?