Decision support systems are interactive, computer-based information systems that provide data and analysis tools in order to assist managers at various levels of an organization in the process of decision-making. Data warehouses have been developed and deployed as an integral part of decision support systems. Data warehouses are increasingly being used by many organizations in many sectors to improve their operations and to better achieve their objectives. For example, a data warehouse application can be used in an organization to analyze customers’ behavior; by understanding its customers, the organization is then able to better address their specific needs and expectations.