  These lectures cover the theoretical structure and phenomenology of some
basic mechanisms for inflation. A full treatment of the problem requires
`ultraviolet completion' because of the sensitivity of inflation to quantum
gravity effects, while the observables are elegantly parameterized using low
energy field theory. String theory provides novel mechanisms for inflation,
some subject to significant observational tests, with highly UV-sensitive
tensor mode measurements being a prime example. Although the ultraviolet
completion is not directly accessible experimentally, some of these mechanisms
have helped stimulate a more systematic analysis of the space of low energy
theories and signatures relevant for data analysis, including searches for
non-Gaussianity and additional structure in the power spectrum. We include a
pedagogical overview of string compactifications, with a focus on candidate
inflatons and their symmetry structure. In the last lecture we attack the
problem of thought-experimental observables in inflation, developing a
generalization of gauge-gravity duality that relies on the structure of the
scalar potential in string theory.
