An HMO is a Health Maintenance Organization. As a member of an HMO, you select a primary care physician from a list of doctors in that HMO's network. Your primary care physician will be the first medical provider you call or see for a medical condition. He or she will make any needed referrals to a medical specialist. Typically, these specialists will be part of the HMO network.
If you obtain care without your primary care physician's referral or obtain care from a non-network member, you may be responsible for paying the entire bill. (with exceptions for emergency care)
With some HMOs, you pay nothing when you visit in-network doctors. With other HMOs there may be a small copayment for the visit or service.
With most HMOs you will not be responsible for paying a deductible.