Abstract　 　　  

   Over cosmic time, half of the radiation emitted by stars has been absorbed by dust and re-emitted at far-infrared and submillimeter wavelengths, so that a full understanding of the star formation history of the Universe requires observations in the submillimeter bands. CCAT will be a 25-meter submillimeter telescope that will enable a broad range of astronomical studies focused on the origins of stars, galaxies and galaxy clusters. Located on a high elevation site in the Atacama Desert of northern Chile, CCAT is designed to provide sensitive high angular resolution observations at submillimeter wavelengths (3.5 arcsec at 350 microns) over a 1 degree field-of-view. The combination of the large aperture telescope, on a prime observing site, with a wide field-of-view, and equipped with state-of-the-art large-format cameras and spectrometers makes CCAT a powerful discovery instrument.