a collection of units that make up a specific area of expertise. Most courses will require students to complete one or two majors. The requirements of a major, including the number of units it contains, will vary from course to course. Additional units studied in the area of a major may enable a student to obtain an e xtended major or a d ouble major . The second major undertaken in a course may be called a c o-major and may involve different rules from the first major.