The Field Explorer enables you to view database fields.

Database fields, formula fields, parameters, and special fields are examples of the types of objects that you can place, move, and resize on your report. You access and insert these objects onto the report from the Field Explorer.
Use the Field Explorer to insert, modify, or delete fields on the Design or Preview tabs. To see the Field Explorer:
Choose the Field Explorer button on the Standard toolbar.
Select the Field Explorer from View on the menu.
The Field Explorer displays a tree view of database fields and special fields that you can add to your report. It also shows formula fields, SQL expression fields, parameter fields, group name fields, and running total fields that you have defined for use in your report.
You can dock the Field Explorer dialog box. In free-floating mode, drag the Field Explorer to any location. Alternately, dock the Field Explorer as a tab, similar to the Design tab.