Data mining is the process of analyzing large databases to discover useful patterns. It involves applying computer-based methods to derive knowledge from large amounts of data. The main components of data mining are knowledge discovery, where concrete information is gleaned from known data, and knowledge prediction, which uses known data to forecast future trends. Data is collected and stored in a centralized data warehouse to allow for easier querying. Common data mining techniques include classification, clustering, regression, and association rule mining. Data mining has various applications in areas such as business, science, medicine, and more to gain useful insights from data. However, effective data mining requires linking multiple data sources which can raise privacy concerns if a person's entire data history is assembled.