MacSpin: dynamic graphics on a desktop computer. The authors describe how MacSpin, a program for dynamic display of multivariate data, and its user interface facilitate a high level of interaction between analyst and data. MacSpin uses rotation to display 3-D scatterplots, and offers such dynamic graphics primitives as animation, identification, and highlighting. With these features the user can visually find trends, clusters, and other patterns in multivariate data as well as highly unusual observations (outliers). The program offers a broad range of data manipulation and calculation features that allow the user to transform, edit, and categorize data as patterns in the display indicate. MacSpin also provides display options and a number of statistical summaries. The authors describe how the program is used on real data. They discuss some history of dynamic graphics, the program’s environment and user interface, and experiences and conclusions