This lecture introduces the physics and hydrology of snow, covering topics such as the physical properties of snow, course information, textbooks, exercises, teaching style, the SNOWPACK model, learning objectives, the cryosphere, types of snow, effects of snow on the atmosphere, snow hydrology, the relevance and importance of snow, and its impact on freshwater resources. The instructor emphasizes the comprehensive understanding of snow physics, snow-atmosphere interaction, and snow modeling, highlighting the significance of snow in modifying energy and water fluxes, climate feedback, and water resource management.