In Chapters 5 and 6, we presented various methods for clustering, including agglomerative clustering, k-means clustering, andmodel-based clustering. In the process of doing that, we showed some visualization techniques such as dendrograms for visualizing hierarchical structures and scatterplots. We now turn our attention to other methods that can be used for visualizing the results of clustering. These include a space-filling version of dendrograms called treemaps, an extension of treemaps called rectangle plots, a novel rectangle-based method for visualizing nonhierarchical clustering called ReClus, and data images that can be used for viewing clusters, as well as outlier detection. We begin by providingmore information on dendrograms.