One of the most striking recent evolutions of physics was to realize that matter as we know it, described by the Standard Model, amounts to less than 5% of the energy density of the universe. This conclusion was brought by several astronomical measurements, and by the measurement of the remnant radiation from the early universe. Even more, among the remaining 95%, a third can be attributed to a form of matter which could be described by a logical extension of the model, but the rest escapes all attempts of microscopic description today.