Polygamy is a type of marriage in which a partner has the right to have more than one spouse. And there are two types of polygamy, they include; polyandry and polygyny. The question about whether polygamy is a crime depends on how you look at it. Polygamy is considered illegal in most European countries and United States, but it is very common in most African countries, Muslim countries and others.
Polygamy, particularly polygyny is common in Africa because most of them practice farming as their source of income, as a result, they marry as many wives as possible so they can have more children that will be helping them on the farm. Polygyny is common in most Muslim countries because Muslims are encouraged to marry as many wives as possible, provided, you will be able to take care of them adequately. Other countries treat polygamy as illegal because they are using it for population control.