According to the U.S. Geological Survey, the polarity of water, due to hydrogen bonding, is responsible for its cohesive and adhesive properties. The positive charge on the hydrogen atom and negative charge on the oxygen ion create forces similar to magnets that hold the water together in cohesion and to other materials through adhesion.
If there were no other forces working on a drop of water, it would be a perfect sphere because of its surface tension, a result of its cohesive nature. However, the force of gravity slightly elongates the sphere into the more familiar drop shape. If the drop hits a pane of glass, the adhesive nature of water causes it to spread into a thin sheet of water. In this instance, the adhesive forces are greater than the cohesive ones. However, if the water drop hits a highly waxed automobile, it forms a bead. The cohesive forces are greater than the adhesive ones in this case.
Sometimes, water's cohesive and adhesive forces work together. If the edge of a strip of cloth is placed into a container of water, the water seems to defy gravity and move up the cloth. Its adhesive nature causes it to cling to the fibers while the cohesive nature pulls other molecules along the fibers, wicking the water through the cloth through the capillary effect.