From its website
The world’s largest online catalog of free education content.
Learn a new language. Study Shakespeare. Discover the cosmos. It’s all possible on iTunes U, home to more than 500,000 free lectures, videos, books, and other resources on thousands of subjects. Among the hundreds of colleges, universities, and elementary and high schools on iTunes U, you’ll find Stanford, Yale, MIT, Oxford, and UC Berkeley, along with other distinguished institutions such as MoMA, the New York Public Library, and more. The free iTunes U app gives you access to an online catalog of free education content from leading institutions. The topics range from science to technology to art to music to philosophy and history.
The University of Chicago adds to our understanding of iTunesU.
iTunes U offers educational multimedia content from hundreds of colleges and universities across the country. It can be accessed through the iTunes Store. If you want to access content from iTunes U, you must first download iTunes to your computer. The University of Chicago launched its site on iTunes U in October 2008.
To get started, set up your iTunesU account from an iPad, iPhone or iPad Touch or Windows PC.