What’s the difference between HMO, PPO, EPO, and POS plans?

These describe how a plan manages access to providers. An HMO requires a primary care physician and referrals and generally covers only in-network care; a PPO is the most flexible (no referrals, some out-of-network coverage); an EPO covers only in-network care but skips referrals; and a POS plan blends HMO and PPO features.