A common-interest development involves a project of individually owned units that have common usage and financial responsibility for common areas. Common examples of this type of development include condominiums, time shares, and planned communities. A major advantage to a common-interest development is the ability of a unit owner to have the benefits of the common amenities without the full cost of them. If an owner owns a pool, they have to bear the full cost of installation and maintenance. In a common-interest development community of 100 units with a common pool, they have to bear one percent of the costs and still have full use of it. To manage the common areas, these developments need a homeowners' association. Builders begin these associations during construction and initial sales. After a certain number of units are under owner control, the association will pass to resident control.