This model represents a simple and generic function. Several variables interact with one another to produce an output, which can then be analyzed to draw conclusions about the real world.
Variables a, b, c, d, and x (time) interact with one another to form the function "model", which is then displayed on the graph.
Because this model is so simple, it can be changed in numerous ways. You can modify the variables, change how they interact, or even create entirely new variables to test their effect on the model.
Whatever variables and values are applied to the function will determine the depiction on the graph. The current model is that of a sinusoidal function, but any range of functions is possible.