stellar and nebular content across this region. Lyman-alpha emitters A key goal of the design of MUSE was to be able to study the progenitors of normal nearby galaxies out to redshifts z > 6. These sources can be extremely faint, in which case they can only be detected using through the emission in the Lyman-alpha emission line, such galaxies are frequently referred to as Lyman-alpha emitters. A common way to study such sources is to use narrow-band imaging, but this technique can only survey a very narrow redshift range at a time – set by the width of the filter. In addition this method is not as sensitive as direct spectroscopic studies because the width of the filter is wider than the typical width of an emission line. Since MUSE is a spectrograph with a 1'x1' field of view, it can be used to search for emission line sources over a wide range in redshift (z = 2.9–6.65 for Lyman-alpha) at the same time. It is expected that the instrument will be used for exposures of up to 100 hours, in which case it should reach a limiting flux of 3x10−19 erg/s/cm2 which is an order of magnitude fainter than current narrow-band imaging surveys. Galaxy evolution MUSE will be a powerful instrument for studying the dynamical properties of galaxies from the nearby Universe out to at least a redshift of 1.4, after which the [O II] forbidden emission line at 372.7 nm disappears off the red end of the spectrograph. At low redshift MUSE will provide two-dimensional maps of the kinematics and the stellar populations in all types of galaxies. It will build on and expand the science done with the SAURON instrument on the William Herschel Telescope, extending it to both larger radii and to more distant galaxies. With the narrow-field mode, MUSE will be able to zoom in on the region around the super-massive black hole at the centre of massive galaxies. It is hoped that this will help astronomers understand the process by which these giants formed - likely through a merging process whereby two black holes coalesce to form a more massive end product and at the same time perturbing the stellar orbits in the centre of the galaxy. At higher redshift MUSE will provide the power to construct maps of the distribution of metals in galaxies and at the same time provide constraints on