ABSTRACT
Our world is filled with data. Every day, whether we realize it or not, we measure and observe data. Data can be as mundane as a grocery list or more complex, a description of the characteristics of a living species or a natural phenomenon, a summary of the results of a scientific experiment, or a record of the events in the life cycle of a mechanical system. Data provide a basis for understanding all kinds of objects and phenomena, allowing us to analyze them and make decisions about them. Grouping data into categories or clusters based on certain similar properties is one of the most important analytic activities, and is the topic of this chapter.
