The frozen form of water is called ice. When water reaches 0 degrees Celsius (32 degrees Fahrenheit) or below, it undergoes a phase change from liquid to solid, forming ice. This crystalline structure is less dense than liquid water, which is why ice floats. Ice plays a crucial role in Earth's climate and ecosystems, affecting weather patterns and providing habitats for various species. It also has numerous practical applications in daily life, from preserving food to recreational activities like ice skating and snow sports.