The development of the internet has changed the way we consume cultural goods. Legally you can find anything from the last album of Justin Timberlake to your favorite episodes of 24 or Grey's Anatomy. Books do not escape this trend. Go to bartleby com or gutenberg org to browse the best classics ever written.
But e-books are not really practical or enjoyable and the offered books are quite old because of the property rights. No problem you can also buy new or used books over the internet.
Online bookstores take an important part in e-business. Obviously you can look at amazon com or ebay com even though the data provided for each book is not as good as on a specialized online bookstore. For example Barnes and Nobles offers a wide selection of books with interesting advice. On its home page you can find selections of books according to your interests with prices almost always lower than in its other bookstores. If you really want to get the price down you can check alibris com a used online bookstore with a very large offer of books. It is especially useful for those looking for books that are not available at your community college or your local bookstore any more or those which are no longer printed.