An HMO (Health Maintenance Organization) provides a standard suite of health-related services, such as doctor visits and prescription drugs, to a large number of patients. They cut costs by economies of scale, but sometimes also by systematically denying claims for benefits unless the patient brings a lawsuit against them.

Doctors worry that HMOs abrogate their right to determine how a patient should be treated. Patients worry that HMOs will screw them. HMOs worry that they're not making big enough profits.

Comedians say that HMO stands for "Hand the Money Over". I'm inclined to agree.