A data warehouse is a centralized repository that stores large volumes of structured and semi-structured data from multiple sources. It is designed to facilitate data analysis and reporting, allowing organizations to aggregate, query, and analyze data efficiently. A data warehouse supports business intelligence (BI) processes by providing a consistent platform for generating insights from historical data. It typically employs ETL (Extract, Transform, Load) processes to ensure data integrity and readiness for analysis, enhancing decision-making capabilities.