Health maintenance organisations (HMOs) are a type of managed healthcare organisation that provides comprehensive medical services to its enrolled members for a preestablished fee, typically paid on a monthly basis, regardless of how often the services are used. HMOs aim to control healthcare costs by emphasizing preventive care and requiring members to choose a primary care physician (PCP) who acts as a gatekeeper, coordinating their care and providing referrals to specialists when necessary. HMOs often have a network of doctors, hospitals, and other healthcare providers that members must use to receive coverage, except in cases of emergency. While HMOs can help to make healthcare more affordable and predictable in terms of cost, they have also been criticised for potentially limiting patients' choice of providers and sometimes prioritizing cost-cutting over the quality of care.