We review the theory of inflation with single and multiple fields paying
particular attention to the dynamics of adiabatic and entropy/isocurvature
perturbations which provide the primary means of testing inflationary models.
We review the theory and phenomenology of reheating and preheating after
inflation providing a unified discussion of both the gravitational and
nongravitational features of multi-field inflation. In addition we cover
inflation in theories with extra dimensions and models such as the curvaton
scenario and modulated reheating which provide alternative ways of generating
large-scale density perturbations. Finally we discuss the interesting
observational implications that can result from adiabatic-isocurvature
correlations and non-Gaussianity.Comment: 51 pages, latex, 16 figures, version to appear in Reviews of Modern
Physic
