This page demonstrates how to use a DataFilter Physlet to modify the data that is being sent from a data source to a data listener. The data source is the cursor shown near the middle of the graph. Whenever this cursor is dragged, it sends [x, y] coordinate pairs its data listeners. One of these data listeners is series 1 of the DataGraph itself. This is how the cursor draws its path. But there is a second data listener on this page. It is an Integrator Physlet contained in the Filters package. The Integrator uses the trapezoidal rule to integrate all incoming data before passing this integral on to its data listeners. The Integrator data is passed on to a DataTable Physlet on this example.