Credit hour is the term universities use to keep track of work completed. Many general-education, major and graduation requirements are defined in terms of specified numbers of credit hours. For example, a degree might require completion of 120 credit hours and include nine credit hours in science coursework. A credit hour represents an hour (or 50 minutes) of instruction over a 15-week period in a semester system or a 10-week period in a quarter system. It is applied toward the total number of hours needed for completing the requirements of a degree, diploma or certificate.