In this chapter we present the basic concepts of information and coding theory. The role of a communication system is to reliably transport information, information which may originate in the form of an analog or digital flow but which always requires processing, so as to protect it against perturbations, and reduce it to a reasonable volume that is easier to transport and to store.

To this end, information theory provides the tools for modeling and quantifying information, while coding theory allows us to build reliable techniques for its transmission and compression.

As reflected throughout this book, probability theory plays a major role in the life of the engineer; not surprisingly, it constitutes the foundations of information theory. Indeed, the problem is here to build probabilistic models able to quantify the basic notion of uncertainty attached to any information, generally unknown, stored, transported, perturbed, etc. We present the bases of these models for multiple applications in the field of telecommunications, and computer science more generally (information storage, compression, transmission, coding and error correction).