A credit is a unit that gives weighting to the value, level or time requirements of an academic course.

Europe
In Europe a common credit system has been introduced. The European Credit Transfer System (ECTS) is in some European countries used as the principal credit and grading system in universities while other countries use the ECTS as a secondary credit system for exchange students. In ECTS a full study-year normally consists of 60 credits. Grades are given in the A-E range, where F is fail. Schools are also allowed to use a pass/fail evaluation in the ECTS system.
Similar systems are widely used elsewhere. Often the word "unit" is used for the same concept.