The surface of a liquid is in contact with some of the vapor phase, and ths is called an interface, a place where two phases meet. Each time a 'bond' between neighbors is broken, energy is required. Thus, it takes energy to move liquid molecules to the surface. The number of molecules at the surface is proportional to the surface area. The viscosity of the oil you use in your car in the winter is lower than that of the oil you use in the summer when measured at the same temperature.
Viscosity is a measure of the ease with which molecules move past one another.
Viscosity depends on the attractive force between the molecules. Viscosity decreases with increasing temperature - the increasing kinetic energy overcomes the attractive forces and molecules can more easily move past each other. Surface tension determines the pressure inside of a bubble. If I have a liquid bubble with gas on the inside and outside, the bubble will try to collapse on the gas inside and cause an increase in pressure inside. Our understanding of surface tension can be made more complete by knowing the energetics of making and breaking of molecular neighbors.