One of the central planks of modern cosmology is the idea of inflation. Originally introduced by Guth  in order to explain the initial conditions for the hot big bang model, it has subsequently been given a much more important role as the currently-favoured candidate for the origin of structure in the Universe, such as galaxies, galaxy clusters and cosmic microwave background anisotropies. This article seeks to give an introductory account of the inflationary cosmology, with the focus aimed towards inflation as a model for the origin of structure.
It begins with a quick review of the big bang cosmology, and the problems with it which led to the introduction of inflation. The modelling of the inflationary epoch using scalar fields is described, and then results giving the form of perturbations produced by inflation are quoted. Finally, the current observational situation is briefly sketched.