Color Glass Condensate and initial stages of heavy-ion collisions

We introduce the concept of Color Glass Condensate, that describes the wave-function of a nucleon or nucleus at high energy. Then, we explain the relevance of this effective theory in the calculation of particle production in heavy ion collisions, and we show how it can be used in order to make predictions for the initial stages of these collisions - in particular in the task of providing initial conditions for hydrodynamical simulations.