The Comprehensive Large Array-data Stewardship System (CLASS) is an electronic library of NOAA environmental data. This web site provides capabilities for finding and obtaining those data. CLASS is an operational component of NOAA's Office of Satellite Data Processing and Distribution (OSDPD) and NOAA's National Climatic Data Center (NCDC). OSDPD and NCDC are organizations of NOAA's National Environmental Satellite, Data and Information Service (NESDIS).

CLASS is NOAA's premiere on-line facility for the distribution of NOAA and US Department of Defense (DoD) Polar-orbiting Operational Environmental Satellite (POES) data and derived data products. CLASS is now archiving and distributing data from NOAA's Geostationary Operational Environmental Satellite (GOES).