Clustering, also known as cluster analysis, is the grouping of a particular set of objects based on their characteristics, aggregating them according to their similarities. Regarding to data mining, this metodology partitions the data implementing a specific join algorithm, most suitable for the desired information analysis.
This method can be considered as a common technique for statistical data analysis, used in many fields, including machine learning, pattern recognition, image analysis, information retrieval, bioinformatics, data compression, and computer graphics.
Everitt, Brian (2011). Cluster analysis. Chichester, West Sussex, U.K: Wiley.
Estivill-Castro, Vladimir (2002). Why so many clustering algorithms — A Position Paper. ACM SIGKDD Explorations Newsletter.