Evolution of Pop III stars

In this paper, first we summarize the many reasons that over the years led to introduce the concept of Pop-III stars. Second, we shortly cast the problem of their mass-scale and initial mass function. Third, we highlight the distinct behavior of zero-metal stars with respect to those of normal and low metal content, and concisely discuss their inner structure and path on the HR diagram in the mass range 0.9 to 100 M. limited to core H- and He-burnings. Finally, are draw some general remarks on the stellar ejecta as a function of the chemical composition, and present some preliminary results concerning the ejecta from massive Pop-III stars due to stellar winds during the early stages.