  The chemical evolution of the Universe is governed by the chemical yields
from stars, which in turn is determined primarily by the initial stellar mass.
Even stars as low as 0.9Msun can, at low metallicity, contribute to the
chemical evolution of elements. Stars less massive than about 10Msun experience
recurrent mixing events that can significantly change the surface composition
of the envelope, with observed enrichments in carbon, nitrogen, fluorine, and
heavy elements synthesized by the slow neutron capture process (the s-process).
Low and intermediate mass stars release their nucleosynthesis products through
stellar outflows or winds, in contrast to massive stars that explode as
core-collapse supernovae. Here we review the stellar evolution and
nucleosynthesis for single stars up to ~10Msun from the main sequence through
to the tip of the asymptotic giant branch (AGB). We include a discussion of the
main uncertainties that affect theoretical calculations and review the latest
observational data, which are used to constrain uncertain details of the
stellar models. We finish with a review of the stellar yields available for
stars less massive than about 10Msun and discuss efforts by various groups to
address these issues and provide homogeneous yields for low and
intermediate-mass stars covering a broad range of metallicities.
