We will review in simple terms how mirror symmetry works for general D-brane configurations, and in particular discuss how abstract mathematical concepts can be realized by physical LG models based on matrix factorizations. As for an application of these methods, we will explain how to explicitly compute exact, instanton-corrected effective superpotentials. (Directions to the room can be found on the triangle website http://brahms.mth.kcl.ac.uk/cgi-bin/main.pl?action=triangle)