I will present the stage-IV Dark Energy Spectroscopic Instrument (DESI). The scientific goals of DESI on dark energy, redshift space distortions and constraints on inflation or neutrino mass will be compared to current measurements and limits set by ongoing experiments, in particular by the SDSS BOSS and eBOSS projects. I will illustrate the construction status of DESI, which is nearing completion, and give the timeline of the five-year survey. The project has successfully observed its first spectroscopic light and is now under commissioning. When it will enter survey mode, DESI is expected to be one of the world’s best facilities for wide-field spectroscopy throughout the decade.