The aim of this little book is to convey three principal developments in the evolution of modern information theory: Shannon's initiation of a revolution in 1948 by his interpretation of Boltzmann entropy as a measure of information yielded by an elementary statistical experiment and basic coding theorems on storing messages and transmitting them through noisy communication channels in an optimal manner; the influence of ergodic theory in the enlargement of the scope of Shannon's theorems through the works of McMillan, Feinstein, Wolfowitz, Breiman and others and its impact on the appearance...