  We provide a very general approach to placing model structures and semi-model
structures on algebras over symmetric colored operads. Our results require
minimal hypotheses on the underlying model category $\mathcal{M}$, and these
hypotheses vary depending on what is known about the colored operads in
question. We obtain results for the classes of colored operad which are
cofibrant as a symmetric collection, entrywise cofibrant, or arbitrary. As the
hypothesis on the operad is weakened, the hypotheses on $\mathcal{M}$ must be
strengthened. Via a careful development of the categorical algebra of colored
operads we provide a unified framework which allows us to build (semi-)model
structures for all three of these classes of colored operads. We then apply
these results to provide conditions on $\mathcal{M}$, on the colored operad
$\mathcal{O}$, and on a class $\mathcal{C}$ of morphisms in $\mathcal{M}$ so
that the left Bousfield localization of $\mathcal{M}$ with respect to
$\mathcal{C}$ preserves $\mathcal{O}$-algebras.
