These lectures concentrate on (nonlinear) stochastic partial
differential equations (SPDE) of evolutionary type. There are three
approaches to analyze SPDE: the "martingale measure approach", the "mild
solution approach" and the "variational approach". The purpose of these
notes is to give a concise and as self-contained as possible an
introduction to the "variational approach". A large part of necessary
background material is included in appendices.