Since their discovery, almost one century ago, cosmic rays provide a powerful tool to investigate phenomena covering both astrophysical and fundamental physics issues. The detection of cosmic rays from low to extreme energies is potentially linked to some of the most intriguing and still unsolved questions of physics and cosmology. Among them, are the nature of the dark matter, the apparent disappearance of the antimatter, the existence of a new exotic form of matter, e.g., strangelets. At the highest energies, the sources and the mechanisms by which cosmic rays are generated and/or accelerated are still a puzzling issue for today's astrophysicists. In order to answer these questions several experiments are planned during the next decade, from space, stratosphere or ground, to perform a multifrequency exploration of the cosmic ray spectrum.