A cloud is a visible mass of tiny water droplets or ice crystals floating in the sky. Clouds form when water vapor in the air cools and condenses into droplets so small and light that they drift on air currents instead of falling to the ground. When billions of these droplets cluster together, they become visible as the white, gray, or dark shapes we see overhead.

Clouds come in many forms. Cumulus clouds look like fluffy cotton balls on sunny days. Stratus clouds spread across the sky in flat gray layers. Cirrus clouds form wispy streaks high in the atmosphere. Storm clouds grow tall and dark, heavy with water that will soon fall as rain or snow.

The word also describes anything that makes things unclear or gloomy. If disappointment clouds your judgment, it prevents you from thinking clearly. A cloud of suspicion might hang over someone accused of wrongdoing. When something troubling happens, people sometimes say there's a cloud hanging over the situation. But just like weather clouds, these troubles often pass with time.

In computing, the cloud refers to storing data on internet servers instead of on your own device, so you can access your files from anywhere.