An Integrated Delivery Network (IDN) is a network of facilities and providers working together to offer a continuum of care to a specific market or geographic area. Developed in the early 1980s, IDNs emerged to address common concerns like capitation, excess capacity, decreased margins, and complaints from patients regarding access. IDNs include many types of associations across the continuum of care and one network may include a short- and long-term hospital, HMO, PHO, PPO, Home Health agency, and hospice services, for example. Multi-hospital systems and mergers may be considered limited IDNs in that different entities join forces to provide care. Some members of a network provide identical or complementary services to patients. Such associations in which a similar level of care is provided by members of a network is sometimes called horizontal integration or, as opposed to different levels of care, or vertical integration, generally seen in the more traditional IDN model.