This module introduces the NPOESS VIIRS imager that will fly on the NPOESS Preparatory Project and the NPOESS satellites. The VIIRS imager has many advanced features that will improve both spectral and temporal resolution. Ninety-five percent of VIIRS data will be available within 28 minutes of overpass time, providing consistent, high-quality, high-resolution data to users. This module covers the improvements to VIIRS by examining the systems that contributed to its development. Special attention is paid to the Day/Night Visible channel as VIIRS will be the first civilian satellite to image atmospheric and terrestrial features with and without moonlight.