9cff82d2__Your_Indispensable_Guide_TIME__What_it_is
[Term] Health-Maintenance Organization (HMO) [Why it matters] An HMO generally requires that enrollees choose a primary-care doctor when signing up for coverage, which helps promote ongoing routine, preventive care. Premiums are lower than traditional health insurance, but patients are severely limited in what procedures are covered and which providers they can see. [What it is] 
An insurer that collects set fees from enrollees for comprehensive medical care, determining which procedures are necessary and limiting services to within a pre-determined network of health-care providers. Blue Cross and Blue Shield are HMOs.
Understanding the Health-Care Debate: Your Indispensable Guide-TIME
What it is