A condominium (or condo) is a form of real estate ownership where you own a single unit in a multi-unit complex, such as an apartment building. While each condo is individually owned, the common spaces are shared by all the owners in the complex. Condo developments are managed by a Homeowners Association (HOA) that collects monthly dues, maintains operations and enforces policies.
Condo buildings are different from co-ops. With a co-op, the homeowners own shares in the corporation that owns the building, not the actual units themselves. Condo buildings have an elected homeowners association that may have members that don't live in the building. Each member of a co-op is expected to serve on the association board at some point during the time he lives in the building. In a tenancy-in-common complex, multiple owners hold joint ownership in a unit whether they're related or not. Different from a condo or a co-op, tenancy-in-common owners can be on the same mortgage and if anyone stops making his monthly payments, the entire building is at risk of foreclosure.