The Multi-Unit Spectroscopic Explorer (MUSE) is an integral field spectrograph installed at the Very Large Telescope (VLT) of the European Southern Observatory (ESO). It operates in the visible wavelength range, and combines a wide field of view with a high spatial resolution and a large simultaneous spectral range. It is specifically designed to take advantage of the improved spatial resolution provided by adaptive optics, offering diffraction-limited performance in specific configurations. MUSE had first light on the VLT’s Unit Telescope 4 (UT4) on 31 January 2014.