Distance Learning, is a field of education that focuses on the pedagogy and andragogy, technology, and instructional systems design that aim to deliver education to students who are not physically "on site". Rather than attending courses in person, teachers and students may communicate at times of their own choosing by exchanging printed or electronic media, or through technology that allows them to communicate in real time and through other online ways. Distance education courses that require a physical on-site presence for any reason including the taking of examinations is considered to be a hybrid or blended course of study.