A Folder is a collection of tables, charts, or other outputs in the Report tree. It is the same idea as having folders on your computer. They created by right-clicking on the Report tree and selecting Add Folder.
A new table can be added to a folder by right-clicking on the group and selecting Add Table. An existing table can be moved into a folder by selecting the table and dragging it into the folder.
Prior to Q5, folders were called groups.