The hydrogen bond between water molecules is the reason why two of water is unique properties, cohesion and adhesion. Cohesion refers to the fact that water sticks to itself very easily. Adhesion means that water also sticks very well to other things, this is why it spreads out in a thin film on certain surfaces, like glass.When water comes into contact with these surfaces, the adhesion forces are stronger than the cohesive forces. That's why instead of sticking together in a ball, it spreads out. Water also has a high surface tension, meaning that the molecules on the surface of water are not surrounded by similar molecules on the molecules on all sides, so they're being pulled only by cohesion by the molecules deep inside. These molecules cohere to each other strongly, but adhere to the other medium weakly. Surface tension makes these water drops round so they cover the smallest possible surface area.