A more thorough explanation:

Common interest developments (CIDs) are properties that are governed by an association, where each unit has an interest in some common area. This means that people who own a unit in a CID share ownership of certain areas, such as a pool or a park, with other unit owners. CIDs can be used for housing or business purposes, but some of the most common forms of CIDs are condominiums and cooperatives.

For example, a condominium complex is a type of CID where each unit owner has an interest in the common areas, such as the lobby, hallways, and elevators. Another example is a shopping mall, where each store owner has an interest in the common areas, such as the parking lot and the food court.

People enter into CIDs for a variety of reasons, such as access to community resources or to create gated communities. Developers use CIDs to create malls and connected chains of stores. For both individuals and businesses, the governing associations take responsibility for governing the common areas and enforcing rules amongst the members. While this allows members to avoid management duties, associations can charge high fees from each member and restrict how members use their unit.