What are waterspouts, and how do they form?

Waterspouts, are they dangerous or not?

What is a waterspout? Waterspouts fall into two categories: fair weather waterspouts and tornadic waterspouts. Tornadic waterspouts are tornadoes that form over water, or move from land to water. They have the same characteristics as a land tornado. They are associated with severe thunderstorms, and are often accompanied by high winds and seas, large hail, and frequent dangerous lightning. Fair weather waterspouts usually form along the dark flat base of a line of developing cumulus clouds. This