The type of cloud known for its fluffy, white appearance is called cumulus clouds. These clouds are characterized by their cotton-like shapes and are typically associated with fair weather. They form as warm, moist air rises and cools, causing water vapor to condense into visible droplets. Cumulus clouds often indicate convection currents and can develop into larger storm clouds, such as cumulonimbus, if atmospheric conditions allow. They are often seen on sunny days and can create a picturesque sky, making them a favorite subject for photography and cloud-watching enthusiasts.