They don't offer degrees but then they don't charge tuition either.
Colleges and universities across the United States are offering free courses online on virtually every subject imaginable, including videotaped lectures by some of their most distinguished professors.
Video-sharing site YouTube recently created a hub called YouTube EDU at youtube.com/edu for the more than 100 US colleges and universities offering free online learning.
Among the thousands of videos on YouTube EDU are the celebrated classroom theatrics of Massachusetts Institute of Technology (MIT) physics professor Walter Lewin, whose clips have been viewed hundreds of thousands of times.
Other leading institutions of higher education posting videos to YouTube include the University of California at Berkeley, Columbia, Cornell, Dartmouth, Duke, Harvard, Princeton, Stanford and Yale.
Interested in dentistry? Then the YouTube channel of the University of Michigan School of Dentistry may be the place for you, serving up a total of 426 videos.
The courses offered on YouTube EDU are free and not for credit but the number of schools offering online classes which count towards a degree is booming.
According to a November 2008 study done for the Sloan Consortium, more than 3.9 million students in the United States were taking at least one online course in 2007, the latest year for which full statistics were available.
That was a 12 percent increase over the previous year, according to Sloan, a non-profit whose mission is to "integrate online education into the mainstream of higher education."
The economic downturn, rising unemployment and higher gasoline costs were cited in the study as factors expected to fuel demand for online education.
Colleges and universities, however, are not the only ones offering free knowledge on the Internet.
Nature Education, for example, has launched Scitable.com, a website it describes as a "collaborative online learning space for science."
"What we wanted to do with Scitable is to bring education roundly into the 21st century, to take advantage of all of the tools and technology available today," said Vikram Savkar, publishing director of Nature Education, a division of Britain's Nature Publishing Group.
"One of our goals is to level the playing field when it comes to science," he told AFP. "Most countries in the world see developing a trained workforce and research cadre in science as key to their national development.
"Science impacts nearly everything - medicine, agriculture, industry - but access to top quality science information and education is unequally distributed around the world," Savkar said.
"In many cases it's expensive. In many cases it's just inaccessible," he said. "One of our major goals with Scitable is to offer very high-quality content and community experts that students anywhere in the world can turn to."
Savkar said Scitable, which launched in January, has users in more than 85 countries tapping into its library of content, joining its community of faculty and students or using its various learning tools.
"This isn't social networking for purely social purposes," he said. "This is about collaborating to teach and learn."
For the moment, Scitable is devoted entirely to the field of genetics. But it plans to phase in content on cell and molecular biology, drug discovery, biotechnology and neuroscience.
"Eventually we'll touch on chemistry and physics," Savkar said. "We'll develop modules on environmental science and ecology."
He said Nature hopes Scitable will eventually be financially self-sustaining through advertising, sponsorship and premium offerings such as tutoring and career placement services.
"We're giving ourselves a good long time - four or five years - to get there," he said.
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