Visual Weight is a characteristic of every element within a composition.  Some things exert a greater pull on the eye than do others in the frame.  This is important because these visual weight relationships determine what a viewer looks in you image, and in what order.  The relative pull of each element compared to the others in an image will determine how a viewer’s eye will move through an image.   This hierarchy of visual weight among the elements in an image creates visual “tension”: the eye is pulled by each element in turn according to its relative visual weight.  The visual weight relationships in an image is one of the strongest influences on how clearly that image conveys your visual message and on the impact it will have with a viewer.  The relative weight relationships among the visual elements of an image is also on of the few things we can influence significantly in post.