Medical insurance is categorized into several primary plan structures designed to accommodate different consumer budgets and healthcare utilization habits. Health Maintenance Organization plans require policyholders to use an in-network primary care physician and obtain referrals to see specialists. Preferred Provider Organization plans offer greater freedom to consult out-of-network doctors without referrals, albeit at higher out-of-pocket costs. Other variations include Exclusive Provider Organizations, Point of Service plans, high-deductible health plans paired with health savings accounts, and government-sponsored programs like Medicare, Medicaid, and specialized state or national public schemes.