Every film has a character that holds everyone else together. We know such people in real life as well. Similarly, in a photograph, there are elements that bind the main subject tightly. They seem most prominent in images where one particular element occupies the overall frame.
For example, a shell lying abandoned on a beach is held together by sand. A photograph of this shell without the expanse of sand would look rather empty. Similarly, a boat floating in a river seems encased by the blue-green water. A person walking on an empty road seems tightly enclosed by the concrete of the road; while a leaf lying in a puddle seems enmeshed by the puddle.
Photograph/Subrata Kar