This book originally grew out of our research in the field of spatial data analysis using clustering techniques. Data analysis becomes quite challenging when several variables are involved. This book deals with various types of clustering techniques and their applications, specially in the field of spatial data analysis in order to find interesting patterns. We have started our book by an introduction to the field of data mining and given special emphasis on cluster analysis which is a task in data mining. Our aim is to impart the knowledge necessary for making proper interpretations, selecting appropriate techniques, understanding their strengths and weaknesses and making it understandable to the readers.