Use the Report Data pane to view the currently defined parameters, data sources, datasets, field collections, and images in your report. The Report Dane displays a hierarchical view of the items that represent data in your report. The top level nodes represent built-in fields, parameters, images, and data source references. Expand each node to view the data items. For example, when you expand a data source node, the datasets defined for that data source appear. When you expand a dataset, its field collection appears. Drag items to the report design surface or to the Grouping pane to link data with selected report items on the report page. For more information, see Working in Report Design View (Report Builder 3.0).
Represents the data that is retrieved from a data source by running one command, for example, a Transact-SQL query that retrieves data from a SQL Server database. A dataset is the parent node for the collection of fields that is specified by the query, and also includes calculated fields. Report Builder supports query designers that help you specify a query. For more information, see Adding Data to a Report (Report Builder 3.0 and SSRS).