The paper discusses the development and application of MODIS (Moderate Resolution Imaging Spectroradiometer) snow-cover products, which are derived from the data collected by the Terra satellite. These products, available since September 13, 2000, through the National Snow and Ice Data Center (NSIDC), offer significant improvements over existing operational snow maps due to their global coverage, 500-m resolution, and ability to distinguish snow from clouds. The snow-mapping algorithms are automated, ensuring consistent data for long-term climate studies. The products include a 500-m resolution swath snow-cover map, daily and eight-day composite tile products, and a 5-km resolution climate-modeling grid product. The paper also presents a case study from March 6, 2000, involving MODIS data and field measurements in Keene, New Hampshire, to validate the snow-mapping algorithms. Issues and limitations, such as the use of the MODIS cloud mask and spurious snow detection, are discussed, along with future enhancements, including daily snow albedo and fractional snow cover.The paper discusses the development and application of MODIS (Moderate Resolution Imaging Spectroradiometer) snow-cover products, which are derived from the data collected by the Terra satellite. These products, available since September 13, 2000, through the National Snow and Ice Data Center (NSIDC), offer significant improvements over existing operational snow maps due to their global coverage, 500-m resolution, and ability to distinguish snow from clouds. The snow-mapping algorithms are automated, ensuring consistent data for long-term climate studies. The products include a 500-m resolution swath snow-cover map, daily and eight-day composite tile products, and a 5-km resolution climate-modeling grid product. The paper also presents a case study from March 6, 2000, involving MODIS data and field measurements in Keene, New Hampshire, to validate the snow-mapping algorithms. Issues and limitations, such as the use of the MODIS cloud mask and spurious snow detection, are discussed, along with future enhancements, including daily snow albedo and fractional snow cover.