Clustering algorithms help group data into similar clusters. This article talks about two types of clustering methods: hierarchical clustering and k-means clustering. Hierarchical clustering creates a tree-like structure by dividing or combining clusters. Single-linkage clustering looks for the closest records in two clusters, while complete-linkage clustering minimizes the distance between the farthest records. The k-means algorithm is a simple and effective way to find clusters in data. The Enterprise Miner clustering node uses SAS's FASTCLUS procedure, which is based on the k-means algorithm.