Snow cover variations over Northern Hemisphere lands result in dramatic changes in the Earth's hydrology and surface energy balance over a range of time scales. These variations play a role in the complex web of feedbacks that control the Earth's climate, and are likely to modulate any climate change that occurs during this century. The ongoing need for reliably observed indicators of climate change, and for refined climate models, to facilitate the detection and attribution of climate change, and the declining global meteorological observation network, underscore the increasing importance of accurate remotely sensed information. A new generation of remotely sensed products in the last decade provides information at unprecedented temporal, spatial, and spectral resolutions. This article reviews the characteristics and theoretical underpinnings of these snow products, shows examples of their application in climatological analyses, and discusses current and future directions in their application and development.