The High Altitude Water Cherenkov (HAWC) gamma-ray observatory has been continuously observing the sky for more than 4 years. Its 1200 photomultipler tubes, contained in 300 water tanks, record the Cherenkov light produced by the secondary particles of atmospheric air showers in the water. The accumulated exposure provides the deepest gamma-ray observations over a large fraction of the sky from a few hundreds of GeV up to a few hundreds of TeV. I will present the observatory and highlight some of the recent HAWC results. In particular, I will emphasise the complementarity with Imaging Atmospheric Cherenkov Telescopes (IACTs), and show a comparison of the galactic plane as observed by HAWC and by HESS.