Ice is water that has frozen solid. When water gets cold enough (32°F or 0°C), its molecules slow down and lock together into a hard, slippery crystal structure. You see ice cubes in your drink, ice covering ponds in winter, and massive ice sheets in the Arctic and Antarctic.

Ice feels cold because it absorbs heat from whatever touches it, which is why it cools your lemonade and why an ice pack soothes a bruise. Ice is also slippery because a thin layer of water can form on its surface, making it perfect for skating but dangerous to walk on. Glaciers, which are slow-moving rivers of ice, carved out valleys and lakes across North America thousands of years ago.

The word also means to freeze something. In hockey, icing means shooting the puck all the way down the ice illegally. Athletes ice injuries to reduce swelling. And when you want to delay or pause something, you might put it on ice by setting it aside for later.