The Visible-Infrared Imaging Radiometer Suite (VIIRS) is a primary sensor on the NPOESS Preparatory Project (NPP) satellite launched on October 25, 2011. VIIRS collects radiometric and imagery data in 22 spectral bands within the visible and infrared region ranging from 0.4 to 12.5 ƒÝm. These data are calibrated and geolocated in ground processing to generate Sensor Data Records (SDRs) that are equivalent to NASA Level 1B products. The VIIRS SDRs in turn are used to generate 22 Environmental Data Records (EDRs) including two Key Performance Parameters (KPPs): Sea Surface Temperature (SST) and Imagery. The VIIRS design and calibration methodology owe much to its MODIS heritage and its measurements are similar. The key design characteristics of the instrument and the manner in which it acquires raw radiometric and imagery data are addressed in this presentation. The ground processing required to convert raw data to Sensor Data Records is also described. Finally, based on the early orbit checkout of the instrument and the ongoing intensive calibration and validation activities, a brief overview of what has been learned thus far about VIIRS on-orbit performance is provided.