What is a plot-enhancing device? examples ?

Many date movies follow a similar simple plot. Boy meets girl, boy loses girl, boy wins girl back in the end. The plot usually refers to the sequence of events and happenings that make up a story. There is usually a pattern, unintended or intentional, that threads the plot together. The plot basically refers to the main outcome and order of the story. There is another kind of plot in literature as well; it refers to the conflict or clash occurring as a part of the story. The conflict usually follows 3 regular formats: a) characters in conflict with one another b) characters in conflict with their surroundings and c) characters in conflict with themselves.