This document provides an overview of data mining, including its definition, origins, necessity, and applications. Data mining is defined as the extraction of implicit, unknown patterns from large data sets by automatic or semi-automatic means. It has its roots in statistics, artificial intelligence, and machine learning. With huge amounts of data now being collected, data mining is necessary to help organizations discover useful knowledge from their data and gain business insights. It has wide applications in areas like marketing, finance, fraud detection, and health care.