  We provide a pedagogical overview of inflation in string theory. Our theme is
the sensitivity of inflation to Planck-scale physics, which we argue provides
both the primary motivation and the central theoretical challenge for the
subject. We illustrate these issues through two case studies of inflationary
scenarios in string theory: warped D-brane inflation and axion monodromy
inflation. Finally, we indicate how future observations can test scenarios of
inflation in string theory.
