First, what significant research resources will you miss if you confine your research entirely, or even primarily, to sources available on the open Internet?
And second, what techniques of subject searching will you also miss if you confine yourself to the limited software and display mechanisms of the Internet?
As I will demonstrate, bricks-and-mortar research libraries contain vast ranges of printed books, copyrighted materials in a variety of other formats, and site-licensed subscription databases that are not accessible from anywhere, at anytime, by anybody on the Web. Moreover, many of these same resorouces allow avenues of subject access that cannot be matched by “relevance ranked” keyword searching.
One can reasonably say that libraries today routinely encompass the entire Internet—that is, they will customarily provide terminals allow free access to all of the open portions of the Net—but that the Internet does not, and cannot, contain more than a small fraction of everything discoverable within library walls.
—Thomas Mann, The Oxford Guide to Library Research: How to Find Reliable Information Online and Offline, 3d ed (Oxford University Press, 2005), xiii.