ABSTRACT
While optimism is regularly discussed among friends, family or even colleagues, and is traditionally associated with beneficial consequences, while its corollary, pessimism, is associated with deleterious effects, it is clear that many scientific studies reveal its conceptual complexity and its consequences. The objective of this chapter is therefore to propose a sorting out of the different conceptual approaches that can be identified in the literature, to propose definitions, to evoke measurement tools, potential consequences in the field of health and finally intervention methods. Limitations and perspectives will of course be proposed for discussion and finally a concluding section will at least momentarily close the debate to which this concept gives rise.
