Part I Agent-Based 1 Introduction.- 2 Simulation and Artificial Life.- 3 Making the Artificial Real.- 4 Modelling in Population Biology.- Part II Modelling Social 5 Modelling for the Social Sciences.- 6 Frameworks and Theories.- 7 A Success for Simplicity.- 8 Conclusions Part III Case Simulation in Demography.- 9 Modelling in From Statistics to Simulations.- 10 Model-Based Demography in I.- 11 Model-Based Demography in II.- 12 Conclusions.