This bond is very weak. Hydrogen bonds are formed easily when two water molecules come close together, but are easily broken when the water molecules move apart again. They are only a small fraction of the strength of a covalent bond, but, there are a lot of them and they impart some very special properties to the substance we call water. Over three-quarters of the planet earth is covered with water. This is because of the tiny, weak hydrogen bonds which, in their billions, hold water molecules together for small fractions of a second.
Water molecules are constantly on the move.
If they are moving fast enough they become a gas. A gas is a physical state of matter where the molecules are far apart and moving very quickly. But, because of the hydrogen bonds, as water molecules come together they stick to one another for a small, but significant amount of time. This slows them down, and holds them closer to one another. Molecular water, therefore is a liquid at room temperature, a fact that is profoundly significant for all living things on this planet.