In higher education a course is a unit of teaching that typically lasts one academic term, is led by one or more instructors (teachers or professors), and has a fixed roster of students. A course usually covers an individual subject. Courses generally have a fixed program of sessions every week during the term, called lessons or classes. Students may receive a grade and academic credit after completion of the course.Courses can either be compulsory material or "elective". An elective is usually not a required course, but there are a certain number of non-specific electives that are required for certain majors.The entire collection of courses required to complete an academic degree is called a program (or programme) of studies.