Once a class is full, you can choose the 'Waitlist me in this class' link to be waitlisted for the class. Note that a class is only full when all places have been taken and there are no places identified as being available at a future date.
You will be advised that your registration has been unsuccessful, but you have been placed on a waiting list. You will also be advised how far down the waiting list you are for the class. Note that waitlisting closes a few weeks before each semester.
You will need to decide whether it is worth waiting for your preferred class, or better to choose another class that you can attend.
It is your responsibility to ensure that you have successfully registered in all classes (even if they are not your first choice) before your classes commence.
Remember - You are able to change your class registration up until the last day to add topics or register in classes. Check the Critical enrolment dates page for details.