A Health insurance policy is a contract between an insurance company and an individual. The contract can be renewable annually or monthly. The type and amount of health care costs that will be covered by the health plan are specified in advance, in the member contract or Evidence of Coverage booklet. The individual policy-holder's payment obligations may take several forms:

• Premium: The amount the policy-holder pays to the health plan each month to purchase health coverage.
• Deductible: The amount that the policy-holder must pay out-of-pocket before the health plan pays its share. For example, a policy-holder might have to pay a $500 deductible per year, before any of their health care is covered by the health plan. It may take several doctor's visits or prescription refills before the policy-holder reaches the deductible and the health plan starts to pay for care.
• Copayment: The amount that the policy-holder must pay out of pocket before the health plan pays for a particular visit or service. For example, a policy-holder might pay a $45 copayment for a doctor's visit, or to obtain a prescription. A copayment must be paid each time a particular service is obtained.
• Coinsurance: Instead of paying a fixed amount up front (a copayment), the policy-holder must pay a percentage of the total cost. For example, the member might have to pay 20% of the cost of a surgery, while the health plan pays the other 80%. Because there is no upper limit on coinsurance, the policy-holder can end up owing very little, or a significant amount, depending on the actual costs of the services they obtain.
• Exclusions: Not all services are covered. The policy-holder is generally expected to pay the full cost of non-covered services out of their own pocket.
• Coverage limits: Some health plans only pay for health care up to a certain dollar amount. The policy-holder may be expected to pay any charges in excess of the health plan's maximum payment for a specific service. In addition, some plans have annual or lifetime coverage maximums. In these cases, the health plan will stop payment when they reach the benefit maximum, and the policy-holder must pay all remaining costs.
• Out-of-pocket maximums: Similar to coverage limits, except that in this case, the member's payment obligation ends when they reach the out-of-pocket maximum, and the health plan pays all further covered costs. Out-of-pocket maximums can be limited to a specific benefit category (such as prescription drugs) or can apply to all coverage provided during a specific benefit year.
• Capitation: An amount paid by an insurer to a health care provider, for which the provider agrees to treat all members of the insurer.
• In-Network Provider: A health care provider on a list of providers preselected by the insurer. The insurer will offer discounted coinsurance or copayments, or additional benefits, to a plan member to see an in-network provider. Generally, providers in network are providers who have a contract with the insurer to accept rates further discounted from the "usual and customary" charges the insurer pays to out-of-network providers.

Prescription drug plans are a form of insurance offered through some employer benefit plans in the US, where the patient pays a copayment and the prescription drug insurance part or all of the balance for drugs covered in the formulary of the plan.

Some, if not most, health care providers in the United States will agree to bill the insurance company if patients are willing to sign an agreement that they will be responsible for the amount that the insurance company doesn't pay. The insurance company pays out of network providers according to "reasonable and customary" charges, which may be less than the provider's usual fee. The provider may also have a separate contract with the insurer to accept what amounts to a discounted rate or capitation to the provider's standard charges. It generally costs the patient less to use an in-network provider.

*Information taken from Wikipedia.org.