In general terms, what is the one-child policy? what are two of the exceptions to the policy?

The one child policy is a birth planning program to control the size of chinas population. This meant each family was limited to having one child. Some exceptions were Chinas ethic minorities such as Uighurs and Tibetans, as well as families residing in the countryside but only if their first born was a girl. Recently a second child is permitted only if both parents were only children.