Claude Shannon’s Theory of Information is one of the greatest theoretical achievements of the twentieth century, with innumerable applications in communication technology. On this basis, the purpose of the present chapter is to offer a balanced panorama of the varied aspects of the concept of information. First, the formalism of Shannon’s theory will be introduced and the conceptual meaning of the First and the Second Shannon Theorem will be explained. Then, the historical roots of the theory will be recalled, stressing the background that World War II supplied to the original development. These aspects will provide the framework to discuss the different interpretations of the concept of information: the epistemic interpretation, according to which information is something that provides knowledge; the physical interpretation, which conceives information as a physical magnitude; and the formal interpretation, which turns information into a merely mathematical concept. Finally, the interpretive debate will be articulated with the many ramifications of the theory in the diverse domains of science.