Distance education can be delivered in a paced format, much as traditional campus based models in which learners commence and complete a course at the same time. Paced delivery is currently the most common mode of distance education delivery. Alternatively, some institutions offer self-paced programs that allow for continuous enrolment and the length of time to complete the course is set by the learner's time, skill and commitment levels. Paced courses may be offered in either synchronus mode, but self-paced courses are almost always offered asynchronously. Each delivery model offers both advantages and disadvantages for students, teachers and institutions.