Coherence is a term used to describe the degree of correlation between the direction of moving objects. In displays containing many moving dots, zero percent coherence means all of the dots are moving independently; 100 percent coherence means all of the dots are moving in the same direction.
It is the degree to which different parts of a text are connected to one another. Coherence exists at both local and global levels of discourse. The property of a story that pertains to how the events of the story are related to each other. In a coherent story, the events in sequence are related to each other in a meaningful way.