Differential scanning calorimetry (DSC) is a powerful tool to address some of the most challenging issues in glass science and technology, such as the nonequilibrium nature of the glassy state and the detailed thermodynamics and kinetics of glass-forming systems during glass transition, relaxation, rejuvenation, polyamorphic transition, and crystallization. The utility of the DSC technique spans across all glass-forming chemistries, including oxide, chalcogenide, metallic, and organic systems, as well as recently discovered metal-organic framework glass-forming systems. Here we present a comprehensive review of the many applications of DSC in glass science with focus on glass transition, relaxation, polyamorphism, and crystallization phenomena. We also emphasize recent advances in DSC characterization technology, including flash DSC and temperature-modulated DSC. This review demonstrates how DSC studies have led to a multitude of relevant advances in the understanding of glass physics, chemistry, and even technology.