The ways of accessing not only information, but also knowledge, how to organize work and the organizations that bring it together, as well as the educational and professional biographies of each person, are changing very rapidly. For decades, life was organized around a succession of stages that were completed one by one and in a predictable order: training, employment, retirement. Today the sequence is no longer fixed: one studies throughout life, one changes profession often, and all of this is linked, alternated, and overlaps in unpredictable ways.