Prostitution is the exchange of sex for economic gain. Even chimpanzees have been observed exchanging sexual favors for food (usually high quality meat). While prostitution is found in all human societies, they differ widely on how they treat these economic exchanges. In some parts of the US, prostitution is a legal - but regulated - activity.  In most of the US individuals can receive fines and imprisonment for engaging in prostitution. As an economic activity, influenced by the laws of supply and demand, prostitution favors females. In some areas and in some circumstances, it is one of the few economic opportunities open to women.