Each insurance plan comes with a network of nurses, doctors and hospitals that will provide you with care at a set price. "Out-of-network" care may be very expensive depending on your plan type. Certain plans also limit the freedom you have to see medical "specialists" within your network. For example, an HMO (Health Maintenance Organization) requires that you see your primary care physician (PCP) for a referral before accessing specialized care.
If you are flexible with your choice in doctors and rarely see specialists, consider an HMO plan. This is a good option if you are on a tight budget and consider yourself relatively healthy.
If you use lots of health care and want the freedom to choose what doctors you see, consider a PPO (Preferred Provider Organization) plan.
If you are comfortable with a closed network, but want to see specialists without a PCP referral, an EPO (Exclusive Provider Organization) might be a good option. You will save money and, compared to an HMO, have a little more flexibility.