The purpose of a data warehouse in business intelligence is to centralize and organize large volumes of data from various sources for analysis and reporting. Data warehouses aggregate structured and unstructured data, creating a repository where organizations can perform complex queries and generate insights. They support business decision-making by providing historical data, trends, and patterns essential for strategy development. By enabling efficient data analysis, data warehouses enhance operational efficiency, facilitate accurate forecasting, and empower businesses to drive informed decisions based on comprehensive data insights.