Helium burning in moderate-mass stars

The evolution of low- and intermediate mass stars at the onset and during core helium burning is reviewed. Particular emphasis is laid on structural differences, which may allow to identify a star's nature and evolutionary phase in spite of the fact that it is found in a region of the Hertzsprung-Russell-Diagram objects from both mass ranges may populate. Seismic diagnostics which are sensitive to the temperature and density profile at the border of the helium core and outside of it may be the most promising tool.