In its first year of observations the Dark Energy Spectroscopic Instrument (DESI) has built the largest map of galaxy redshifts to date, spanning the nearby universe to 11 billion light years. Accurate measurements of how galaxies distribute and cluster within this map allow us to trace the expansion history of the Universe to unprecedented precision and understand what role dark energy played in such process. In this talk I will present the first set of DESI cosmological results, coming from measurements of the baryonic acoustic oscillations (BAO) characteristic scale.