Moodle provides for a range of enrolment methods which can broadly be categorised as:
Registered students are normally automatically enrolled on the Moodle courses corresponding to their units of study. Some staff are also enrolled via automated means. Student automated enrolments appear as LSE IMS Messaging on Moodle. Teacher (Editor)s cannot unenrol students. The only way an automatically enrolled student can be unenrolled is if the student drops the course on LSE For You (LFY).
Staff are normally manually enrolled by central administration or by their local administrators. Once staff are enrolled at an appropriate level, they can carry out further enrolments e.g. of other staff or students but only at a role lower than theirs e.g. Teacher (Editor)s can enrol non-editing Teachers and below but not other Teacher (Editor)s. See Enrol, unenrol and change the access level of course participants for more information.
If this has been enabled on a course, then users can enrol themselves. This is normally only used for auditing students at LSE. However, it can be provided for multiple roles should the course manager require it. It may also be associated with a password that is given out on a selective basis during lectures, or individually by a member of staff to an interested student. If your course requires self enrolment and you need further help contact firstname.lastname@example.org
Strictly speaking, this is not an enrolment method as guests are not enrolled. If a course allows guest access then anyone can see its visible content. However, they cannot participate in any activities. It can be used with or without a password.