The growth of cosmological density perturbations

These lectures present the theoretical basis of our understanding of the large scale structure of the universe. The different types of primordial metric fluctuations are described as well as their evolution from super-Hubble to sub-Hubble scales in the local universe. It is shown how the only adiabatic mode can explain what we have so far observed of the large-scale structure of the Universe. These notes also present our current understanding of the origin of these metric perturbation in the inflationary context. Various models of inflation are presented together with their motivations. These notes are completed with a description of the issues raised by the search of primordial non-Gaussianities. Those issues are presented both in the context of classical perturbation theory and in the physics of the early universe.