Numerical relativity simulations of binary black hole mergers played a crucial role in the calculations of the gravitational wave signals that were just observed by the advanced LIGO and Virgo detectors. In this talk, I will briefly review the history of simulation efforts to model these systems and provide an overview on the field of numerical relativity, including the development of key ideas that led to the 2005 computational breakthrough. I will also present some of the most recent progress and challenges in calculating gravitational radiation waveforms for interpreting gravitational wave observations.