 Enrollment Key is a useful way to prevent users from gaining unauthorized access to a course despite the fact that they might be legitimate users of the learning management system. You just may have a reason not to grant them access to a particular course. So logged into the said course as a teacher, go to the settings block, course administration, resources, enrollment methods, go to self-enrollment, give this instance a name and we need to enable self-enrollment, now place an enrollment key. This is essentially a single-use password that needs to be given to the users that you wish to grant access, course access to. You determine the role you wish was signed and the enrollment period and so forth, custom welcome message, save changes. So if we log out as the teacher and we come back in as a student who wishes to gain access to a particular course, then prompted for the enrollment key, the single-use password that should be provided by the teacher. So they enter that, click enroll me, they're enrolled in the course.