.
Surface
tension of water is the a property
of a surface (interface) between a liquid (water) and a gas (air). The surface
of the liquid behaves like a tight, elastic membrane.
The surface tension of water makes a water drop look spherical in the air (Photo 1 - 3), even allows a couple of 2 water striders to move freely on the water surface of a pond (Photo 4) or prevents water from flowing out of an 2-ml ampoule (right Photo).