Our current knowledge of the solar wind derives from in-situ observations in interplanetary space, and from remote sensing observations of the corona. Model computations have been instrumental in trying to bridge the gap between these two regions of space where no measurements are available. Theoretical studies have often been the driving force behind new explorations. It is clear that a complementary approach of theoretical studies, numerical models and observations are essential for achieving a more profound understanding of what heats the corona and accelerates the solar wind. The UVCS instrument on SOHO is one of the frontier facilities to shed light on the properties of the acceleration region of the fast and slow solar wind, as already demonstrated by the data returned so far. It seems therefore extremely timely to assess where we stand at present in our current knowledge of the solar wind from a theoretical standpoint.