Distance learning systems have become quite common since the advent of the Internet, but they have actually been in existence for over 250 years. Correspondence courses, in which a student would write letters containing coursework to instructors a distance away, were common throughout the early part of the 20th century, and today they still exist in some form: e-mail can be used to communicate with instructors of a variety of courses. Online modules that use web conferencing, audio clips, and message boards are common distance learning systems as well, and they can now be used to obtain professional certificates and degrees.
High school students now have the option of using distance learning systems to obtain a high school diploma or GED as well. Most of these options utilize the Internet as the primary mode of communication. Lessons can be taught via video conferencing or pre-recorded video lessons; communication takes place via e-mail or online message boards. Mp3 files can be downloaded so students can hear lessons as well, and other accommodations can be made for students of different learning styles. Students who have difficulty in social situations may turn to distance learning systems to obtain a high school diploma, and students who live in extremely rural locations can also access materials without having to travel long distances to a physical location.
College coursework is now commonly available as distance learning systems. A student can earn professional certificates, associate's degrees, bachelor's degrees, master's degrees, and even to a certain extent doctorate degrees. The distance learning systems are sometimes limited by the subject matter, however, as some degree programs require lab work; students must be on-site for such work, which means the distance learning option will only be part of the curriculum. Some programs, however, can be conducted exclusively through distance learning programs.
Two general classifications of distance learning systems exist: synchronous and asynchronous. Synchronous courses are conducted at a specific time, just like in-classroom classes, and all students in the class must be logged into a website or other portal during the class time to participate in the curriculum. Asynchronous courses allow the student to work at his or her own pace, and he or she can access course materials at any time throughout a semester. Each type of class structure has its advantages and disadvantages; the student must decide before enrolling which learning style will work best for him or her.
