Water Density – Why does ice have a lower density than water?

Question

Can someone explain me why is ice less dense than water?

As I know, all solids are usually denser than the liquids (correct me if I am wrong).

Answer 1

Due to the crystal structure of the solid phase of water, the molecules arrange themselves in a rigid, ordered fashion and end up being, on average, farther apart from each other (than they are in the liquid phase), and thus less dense. Less dense things float because of buoyancy.