The 186th IAU Symposium came at an exciting and perhaps even historic time for extragalactic astronomy. New spacecraft observations plumbed the depths of the universe out to redshifts of five, while revealing astounding details of nearby galaxies and AGN at intermediate redshifts. Theoretical ideas on structure formation, together with results from detailed numerical modelling, created a comprehensive framework for modelling the formation of galaxies and the transformation of galaxies by interactions and mergers. All these strands came together at the Symposium, as participants glimpsed a developing synthesis highlighting galactic encounters and their role in the history of the universe. This volume offers professional astronomers, including PhD students, an overview of the rapidly advancing subject of galaxy interactions at low and high redshifts.