Patient contribution is an important part of healthcare, and it can take many forms. One of the most common forms is copay, which is a five-letter word that refers to the amount of money that a patient pays out-of-pocket for a medical service or prescription. Copay is typically a fixed amount that is determined by the patient's insurance plan. It is usually a small percentage of the total cost of the service or prescription, and it is due at the time of service.