Our knowledge of the cosmic composition has changed drastically over the last two decades. Observations of Type Ia supernovae, accurate distance indicators in cosmology, were first to show that the expansion of the Universe is speeding up, contrary to the expectations from the attractive nature of gravity on ordinary matter. Thus, the current standard model of cosmology is based on the existence of "dark matter" and "dark energy". Understanding the nature of the dark universe remains among the most pressing issues in contemporary physics. Since the early days of supernova cosmology, technological advances have allowed us to drastically increase the science reach: the new generation of optical cameras used to search for supernovae can image a large fraction of the observable sky in a single night. We are starting to discover very rare and precious astronomical systems, e.g., gravitationally lensed supernovae. Furthermore, we can explore new time scales for transient phenomena, allowing us to chart new physics territories. In this talk I will review the recent history and exciting future of supernova observations in cosmology.