What is surface energy?

Surface energy is defined as the excess energy at the surface of a material compared with the
bulk material itself.

When a liquid comes into contact with a surface, if the molecules of the liquid are attracted to each other more strongly than to the surface, then the liquid won’t wet the surface very well, instead forming beads. Conversely, if there is a larger attraction to the surface then the liquid will spread out more.

It follows that if a particular surface has a higher surface energy it will wet more easily and, since
the ability to wet a surface is in turn a simple definition of the adhesion characteristics of the
surface, it will be easier to glue/print/paint or bond to that surface.