ETL processes are defined in Integration Services packages. A package consists of a control flow definition, which describes the high-level flow of a process. A process flow can invoke a data flow, which describes the details of any transformations a data source must go through before being stored in a destination. Packages make it easy to intercept and redirect bad data, and simplify maintenance by making it easy to see what processes and transforms the data is undergoing. You use the BI Development Studio to create and debug your packages and to deploy your solution to other environments such as test and production. In those other environments, connections to data sources and destinations, as well as variables and other parameter settings, can be set at runtime through environment variables, XML files, and database tables.