Scientific knowledge grows at a phenomenal pace--but few books have had as lasting an impact or played as important a role in our modern world as The Mathematical Theory of Communication, published originally as a paper on communication theory in 1948. Republished in book form shortly thereafter in 1949, it has since gone through four hardcover and sixteen paperback printings. It is a revolutionary work, astounding in its foresight and contemporaneity. The University of Illinois Press is pleased and honored to issue this commemorative 1998 reprinting of a classic. Shannon's major precept, that all communication is essentially digital, is commonplace among the digitalia that many wonder why Shannon needed to state such an obvious axiom.