EnVision, a low-altitude polar orbiter, is the M5 mission candidate in the ESA Science Programme. It will carry 5 instruments and 1 experiment (an S-band Synthetic Aperture Radar, a Subsurface Radar, 3 spectrometers and a radio science experiment). EnVision will investigate Venus from its inner core to its atmosphere at an unprecedented scale of resolution, characterising in particular, core and mantle structure, signs of active and past geologic processes and looking for evidence of the past existence of oceans. EnVision will help understanding why the most Earth-like planet in the solar system has turned out so differently, opening a new era in the exploration of our closest neighbour.