A technique for taking spectra of many objects in a single field of view. It uses a mask with apertures that precisely match the locations of various targets on the sky. The mask is inserted into the field of view of a telescope and optical fibres feed the light from each aperture into a spectrograph. In this way the spectra of thousands of objects can be obtained simultaneously over an area of sky several degrees wide. Telescopes capable of taking multi-object spectra include the Very Large Telescope in Chile, the Anglo-Australian Telescope, the Gemini North and South telescopes, the Southern African Large Telescope, and the Chinese LAMOST telescope. A related technique for small telescopes is objective-prism spectroscopy, in which a thin prism (or a diffraction grating) is used to disperse starlight before it enters the telescope. This method was used, for example, to observe and classify stellar spectra for the Henry Draper Catalogue.