A cornerstone in arranging the item list is through indenting and outdenting items. When you indent an item, the task above it will become a Sub project, which will contain all indented items underneath it. Sub projects work the same as standard items, but can contain other tasks and be collapsed to hide all indented items.
1. Right-click an item in the Planning view.
2. Select Indent.
The selected item is indented and the item above is transformed into a sub project.
3. To outdent an item, right-click it and select Outdent.
The selected item is outdented.
If this was the only indented task under the sub project, that sub project will revert to a standard item.