AbstractIn these last years a huge amount of both spectroscopical and photometric data has provided a plain evidence of the fact that Galactic globular clusters (GCs) host various stellar sub-populations characterized by peculiar chemical patterns. The need of properly interpreting the various observational features observed in the Color-Magnitude Diagrams (CMDs) of these stellar systems requires a new generation of stellar models properly accounting for these chemical peculiarities both in the stellar model computations and in the color - T_eff transformations. In this review we discuss the evolutionary framework that is mandatory in order to trace the various sub-populations in any given GC.