Snow is solid precipitation formed when ice crystals grow in clouds, attracting supercooled water droplets and freezing into hexagonal shapes like platelets, needles, and columns. These flakes typically develop within larger weather systems, such as mid-latitude cyclones and cold or warm fronts, but can also result from lake-effect storms or mountain elevation effects. Once accumulated, snowpacks undergo metamorphosis through sintering and freeze-thaw cycles, and in persistently cold climates, they can compact into massive glaciers. Snow dominates the polar regions and the northern half of the Northern Hemisphere, while in the Southern Hemisphere it is mostly confined to mountainous areas—except for Antarctica. Beyond shaping the landscape, snow profoundly influences human life, affecting transportation, agriculture, winter sports, and warfare, while also serving as a critical insulating layer that protects plants and animals throughout the winter.