Credit is the recognition for having taken a course at school or university, used as measure if enough hours have been made for graduation.
In high schools in the United States, where all courses are usually the same number of hours, often meeting every day, students earn one credit for a course that lasts all year, or a half credit per course per semester. This credit is formally known as a Carnegie Unit. After a typical four-year run, the student needs 26 credits to graduate (an average of 6 to 7 at any time). Some high schools have only three years of school because 9th grade is part of their middle schools, with 18 to 21 credits required.
In Canada, credits can be earned at the end of a course in high school. Earning a credit depends whether a person passes the course or not. A certain number of credits are required to graduate high school. The course credit system is similar to the one used in the United States.
In a college or university in the United States, students generally receive credit hours based on the number of "contact hours" per week in class, for one term; more well known as Semester Credit Hours. A contact hour includes any lecture or lab time when the professor is teaching the student or coaching the student while they apply the course information to an activity. Regardless of the duration of the course (i.e. a short semester like summer or intersession) and depending on the state or jurisdiction, a semester credit hour (SCH) is 15-16 contact hours per semester. Most college and university courses are 3 Semester Credit Hours (SCH) or 45-48 contact hours, so they usually meet for three hours per week over a 15-week semester.
Homework is time the student spends applying the class material without supervision of the professor: this includes studying notes, supplementary reading, writing papers, or other unsupervised activities such as labwork or field work. Because students are generally expected to spend three hours outside class studying and doing homework for every hour spent in class, 15 SCH is the typical full course load, although many colleges consider 12 SCH a minimum full-time load for financial aid and other purposes. Some schools set a flat rate for full-time students, such that a student taking over 12 or 15 credit hours will pay the same amount as a student taking exactly 12 (or 15). A part-time student taking less than 12 hours pays per credit hour, on top of matriculation and student fees.