The Maunakea Spectroscopic Explorer (MSE, formerly Next Generation CFHT) is a project to upgrade the CFHT into a survey telescope with a 11.25-meter mirror and a dedicated, heavily multiplexed, wide-field spectrograph with a wavelength coverage of 0.36-1.8 micron and multiple spectral resolutions (R~2500-40000). I will present the project in general as well as the transformative science that could be made possible by MSE in areas as diverse as tomographic mapping of the interstellar and intergalactic media; the in-situ chemical tagging of the distant Galaxy; connecting galaxies to the large scale structure of the Universe; measuring the mass functions of cold dark matter sub-halos in galaxy and cluster-scale hosts; reverberation mapping of supermassive black holes in quasars.