Sea ice is frozen seawater that forms in the polar regions and covers parts of the ocean's surface. It plays a crucial role in regulating the Earth's climate by reflecting sunlight and helping to maintain cooler temperatures. Sea ice can vary in thickness and extent, depending on seasonal changes and environmental conditions. The formation of sea ice typically occurs during the winter months when temperatures drop. As the ice melts in the summer, it creates a habitat for various marine species, including polar bears and seals. The health of sea ice is vital for the overall ecosystem and is affected by climate change.