Enrolment
From MoodleDocs
Course enrolment is about assigning users the role of student in a course.
By default, students can enrol themselves on whatever courses they choose. This method of enrolment is called internal enrolment. You can restrict users from enrolling on whatever courses they choose by setting an enrolment key.
Whilst internal enrolment is an effective and efficient way to of managing course enrolment, particularly if you don't have a lot of courses, Moodle also provides a number of other enrolment methods, called Enrolment plugins.
