IBM DataStage is an ETL (Extract, Transform, Load) tool used to design and manage data integration processes. It enables the extraction of data from various sources, its transformation to meet business requirements, and its loading into target databases or data warehouses. DataStage supports parallel processing, which helps in handling large volumes of data efficiently. It also integrates with other IBM tools and provides a graphical user interface for designing data flows, making it easier for developers to build, test, and deploy complex data transformation tasks.