Stacks on the Desktop
The desktop can quickly clutter up if you use iCloud or even if you just love to store items you are working on there.
With macOS Mojave, your desktop now has the ability to Stack related documents together so that your desktop is cleaner and items are easier to find.
You can group by file type, a variety of date information or by tags. You can scroll through the various stacks and find what you are looking for easily.
This is a feature you can choose to use, or choose to ignore if you don't like it.