Clustering is the process of grouping physical or abstract objects into classes of similar objects. These groups of similar objects are called clusters. Objects in one cluster are very similar to other objects in that particular cluster but very dissimilar when compared to objects in other clusters. Portraying data by fewer clusters necessarily loses certain fine details (akin to lossy data compression), but achieves simplification. It portrays many data objects by few clusters, and hence, it models data by its clusters. Clustering analysis is broadly used in many applications such as market research, pattern recognition, data analysis, and image processing.