Massachusetts Institute of Technology first announced its plan to offer free online courses through its OpenCourseWare (OCW) program in 2001. Students who study online have access to course materials, reading lists, tests and quizzes, but they are not able to interact with students or the professor. MIT now offers over 2000 undergraduate courses from more than 30 departments and many other universities, such as Yale, have started using the OCW platform as well. The name OpenCourseWare is intentionally reminiscent of open-source software.
Some universities, such as the University of California at Berkeley, have chosen to offer their courses for free in the form of podcasts, audio files that can be listened to online or downloaded and listened to later. Online students have access to the course's lectures and can buy the textbook for themselves. The podcasts arguably have less value than OpenCourseWare because they do not provide a means of testing your knowledge, which OpenCourseWare does. Economics classes are particularly difficult in this method because students can only hear the professor; they cannot see the equations and graphs that the professor presents.
Virtual universities are the newest form of an old educational model: distance learning. The universities exist primarily online, though students may occasionally meet with tutors or assistant professors in person. The Open University is a UK-based university that offers most of its online course material for free through its OpenLearn program. US students, or others not in the UK, can also access Open University's free online economics courses through the OpenLearn platform. And, unlike OpenCourseWare, OpenLearn also allows interaction between online students so that learning isn't strictly a solo activity. Registration is required and students will have to pay if they want to take part in any of the Open Universities degree-granting programs.
Nearly all colleges and universities allow students to audit classes, essentially taking the class but without fees, grades or course credit. State-run universities often allow non-students to audit classes as well; this is seen as furthering the universities' public service goals. Academic auditing policies vary widely among private universities, but many leave the final decision in the hands of the course instructor. A polite email can often be enough to gain a professor's permission.