In what does the difference between analog and digital consist? What are the benefits of a digital solution with respect to a parallel analog solution? This is not a purely intellectual conundrum since managers and politicians make conspicuous investments in analog and digital infrastructures and systems. Scientists from different fields are searching for the appropriate definition of what is digital and analog, but the profile of the technologies that have changed mankind's lifestyle and the history of the world still resist the scrutiny of thinkers. The present work deriving from a long-term theoretical inquiry suggests some keys to interpret the digital and the analog machines. The author claims that understanding analog versus digital is not as easy as comparing the adjectives digital/continuous or natural/artificial, and conducts an accurate analysis of the systems' core. Frequently the author follows an historical perspective and does not refrain from comments on linguistics, anthropology, psychology, and other fields related to the information domain. Book jacket.