A stage is a subset of all the pages in the UDI Wizard configuration file that an MDT deployment scenario uses. When you start the UDI Wizard using the UDI Wizard task sequence step, the /stage parameter specifies the stage to run, which in turn specifies the set of pages to use. You can preview how wizard pages will appear in a stage by clicking Preview in the Preview Wizard group on the Ribbon. You can use a UDI stage in more than one MDT deployment scenario, even though the UDI stage is defined only once in the UDI Wizard Designer. For example, the NewComputer stage can be used in the MDT New Computer and Replace Computer deployment scenarios.