The Dark Energy Spectroscopic Instrument (DESI) is building the largest 3D map of our universe to measure its expansion history over the past 11 billion years, and, thereby, study dark energy. With the analysis of Baryon Acoustic Oscillations from its three-year (DR2) data set, DESI confirms the tantalizing hint of time-varying dark energy of the first-year studies. In this seminar, I will give an overview of the DESI experiment and present the most recent results on dark energy and neutrino masses using DESI data.