2.6 Object collections
After you start creating objects, the 3D Viewport will probably become
crowded with lots of 3D Models. In Blender, we can work with a tool
called Collections that lets you create something similar to groups. By
using Collections, you have much better control over complex scenes.
The Collections appears in the Outliner Editor in the top right of your
default user interface (Figure 2.29).
Figure 2.29 - Outliner Editor
At the Outliner, you have the Scene Collection, which is the base for all
Blender files. Even if you don't want to use any new Collections, it will
appear as the base for your scene.
You also have a "Collection" that has your default Cube, Camera, and
Lamp. All objects you add to the scene will go to the Active Collection.