The multiple stellar population phenomenon in Galactic Globular Clusters: the observational and evolutionary frameworks and its implication for the Galaxy formation

The discovery of the presence of distinct sub-stellar populations in Galactic Globular Clusters represents one of the most astonishingly results in the field of Stellar Astrophysics. Not only it has severely challenged our view of these stellar systems as the prototypes of Simple Stellar Populations, but it has posed a number of - still largely unsolved - issues related to the physical processes responsible of the origin and properties of these multiple stellar populations. During this presentation, we discuss the observational framework and the theoretical evolutionary scenario that is used for explaining (some of) the various empirical evidence. A general overview of the proposed scenarios for the formation of multiple stellar populations is also provided by emphasising the many open questions. The Multiple Stellar Population Phenomenon will be discussed in the cosmological context of the  Galaxy formation.findings.