Breakup of liquid drops occurs in several natural and industrial settings. Fully resolved volume of fluid based simulations presented in this study reveal the complete flow physics and droplet dynamics that lead to the breakup of a drop in the moderate Weber number regime. We have investigated the effects of density ratio and Reynolds number on the initial dynamics of drop deformation. A density ratio-Weber number phase plot is presented that indicates the variation in the deformation of the drop at various density ratios and Weber numbers. We show that the initial deformation and dynamics of the droplets at low density ratios is significantly different from that observed at high density ratios. We also study the temporal characteristics of the initial droplet deformation and motion. (C) 2019 Elsevier Ltd. All rights reserved.