The HMO

Perhaps the most talked about type of insurance, the Health Maintenance Organization. 

The HMO works through a gatekeeper doctor system. You designate a doctor to be YOUR doctor. You must go through that doctor to see any specialist or any other doctor - hence the gatekeeper. 

This means that the insurance company has the right to not pay any claim in an instance where you took it upon yourself to schedule an appointment with an OB-GYN, Urologist, whatever. 

The reasoning behind an HMO is that this one doctor will get to know you. This person will see you for everything and can stress preventative care. 

Critics of HMOs state that oftentimes the Doctor works directly for the HMO (or insurance company), thus having a vested financial interest in not encouraging you to get a second opinion, go to a specialist, etc. (his companies profits go down!). 

In the end you must be the judge if the HMO works correctly for you. If you have a doctor you trust and have a relationship with that could be your HMO doctor, perhaps this is a good option.