Getting a grasp on the basics of health insurance...

Preventative Services - Services categorized as preventative services are generally those that can detect problems earlier when it is easier, safer and less expensive to treat the patient. Health insurers encourage patients to have preventative services by covering them before the deductible is met. Additionally, preventative services are often fully paid by the health insurer - the patient has no financial liability.

Co-Pay - Co-pay is the amount of money the patient has to pay for a specific service or benefit.  Co-Pays are most commonly used in HMO plans (i.e. $25 co-pay for a doctor visit).  It was a way for HMOs to share the cost of the service with the patient.  More and more PPO plans are also requiring patients to pay a co-pay for surgical services, drugs etc. in addition to paying their deductible and co-insurance amount.

Co-insurance - Co-insurance is similar to co-pay, in that it is a way for the health plan to share the cost of service with the patient.  The main difference is that it doesn't limit the patient's liability to a specific dollar amount.  The patient is liable for a defined percentage of the allowance amount. The allowed amount is negotiated between the provider and the payer. Therefore, the patient's liability is often different even if the type of provider is the same. In other words, the rates paid by the health plan to provider A are often different than the rates paid to provider B.  If the rates paid to provider A are more, the patient will pay more.