This chapter explores the fundamental concepts of data warehousing, emphasizing its role as a separate analytical data store designed to support complex decision-making through trend and pattern analysis. It highlights key functional and technical differences between application-oriented operational systems and subject-oriented data warehouses, which provide an integrated, historical, and time-variant view of enterprise-wide data. Finally, the text outlines the core components of a data warehousing system, including the critical ETL infrastructure, and details the iterative steps of the development lifecycle ranging from requirements collection to deployment and maintenance.