The clustering methods like K-means or Expectation-Maximization are suitable for finding ellipsoid-shaped clusters, or at best convex clusters. However, for non-convex clusters, such as those shown in Figure 15.1, these methods have trouble finding the true clusters, since two points from different clusters may be closer than two points in the same cluster. The density-based methods we consider in this chapter are able to mine such non-convex or shape-based clusters. Figure Density-based Clustering