It is often said that we now live in an information society. What is actually information? A sequence of 0 and 1 symbols, or rather an ensemble of systems with two states encoding these symbols? Presently, even in the most miniaturized computer chip, a binary digit, nicknamed  "bit" , corresponds to a complex electronic device housing millions of interacting particles. How should we understand information processing when each bit is carried by a single physical particle such as an atom, an electron or a photon? Inversely, can we consider the motion of all elementary particles as a computation that the universe is carrying on? In the last 15 years, physics has witnessed a rapid development of ideas and experiments, that have illustrated the fundamental role played by information in physical laws. The deep connection between physics and information is exploited in novel types of ultra-sensitive measurements, the development of a quantum computer, and in the now commercially available secure communication systems based on quantum cryptography. This symposium discusses the emerging features of information processing quantum machines.