Interplay of cosmological simulations and perturbation theory

Perturbative methods for predicting nonlinear galaxy density fields have proven to be accurate, reliable and flexible enough to be one of the main tools for interpreting large observational data sets. I will review some of the main successes of these approaches and highlight the reasons for why we believe them to be nearly optimal for current and upcoming spectroscopic galaxy surveys. In the second part of my talk I will focus on the interplay of perturbative methods and cosmological simulations and give a number of examples which show how one can benefit from the other.