In this chapter,models ofmass 1, 5, and 25 M☉ and of population I composition (Z = 0.015 and Y = 0.275) are evolved through all phases of hydrogen burning up to the point when helium is ignited in a hydrogen-exhausted core. The model masses have been chosen with the aim of representing three broad classes of stars. Models of mass less than 0.5 M☉ have been excluded from consideration not only because they evolve on a time scale much longer than a Hubble time, but, because they remain completely convective throughout their nuclear burning lives, they can be described adequately by a sequence of polytropes, as discussed in Section 5.6, without invoking the elaboration of an evolutionary calculation. The 1 M☉ model is representative of a class of stars which evolve in less than a Hubble time into red giants with an electron-degenerate helium core and ignite helium in a semiexplosive fashion. These stars, of mass extending to ˜2.25 M☉, eventually become AGB stars with a carbon-oxygen core and, after ejecting a nebular shell, evolve into CO white dwarfs of mass ˜0.55 M☉ The 5 M☉ model is representative of stars in the approximate mass range 2.25 <M/M☉ <10.5 which ignite helium under non electron-degenerate conditions, but during and following the quiescent helium-burning phase evolve in a fashion similar to the evolution of lower mass stars during and after the quiescent helium-burning phase.