This textbook offers a comprehensive introduction to the geophysics of the cryosphere—Earth’s sphere of snow and ice—intended for advanced undergraduate students in geophysics, geography, geology, and environmental sciences. Unlike broader climate-focused or geographically descriptive volumes, this book provides a structured, physical understanding of snow and ice processes in high-latitude and high-altitude environments. Chapters cover the physical properties of snow and ice, the evolution of seasonal snow cover, the flow and mass balance of glaciers and ice sheets, and the behavior of floating ice on lakes, rivers, and seas. The book also explores the cryosphere’s role in climate systems and its future under changing conditions. Developed from long-standing courses at the University of Helsinki and international winter schools, this book includes end-of-chapter study problems and a compact annex of key constants and formulas. It is equally useful as a coursebook or reference for researchers in Earth system sciences working with cryospheric elements.