We have all seen different ways to present a model. A sculptor might create a small three-dimensional model out of clay for a larger piece she plans to chisel from marble. An architect might create a scale model of a new building with balsa wood, paper, and other materials to better understand the proportions and balance of the building and its surroundings. Software developers create visual models to tell specific stories about a system, with each diagram depicting one aspect of that story. UML models are a very effective way to tell the story of developing a software system, starting with use cases, moving through analysis and design, and finally implementation and deployment. Each part of the story should trace to each other part so that the viewer can follow from one model to the next without becoming lost. These model links are almost as important as the content of the model itself, because you can get the full story only through this progression. Think of the plot in a novel; each new incident typically relates in some way to an earlier incident, which moves the story along and gives it consistency and cohesiveness.