You can think of Plasma Activities as being Desktops in another dimension –
- Each Plasma Desktop can use Activities as an extension to whatever is being executed on that Desktop.
I tend to use Activities during schooling sessions –
- The slides for the schooling session run on Desktop and, Konsole sessions demonstrating CLI usage are running in parallel in a Activity – switch between Activities with [ Meta + Tab ] or,
in the other direction [ Meta + Shift + Tab ]
Another – more than 10 years old – view of Plasma Activities is here: <https://www.linux.com/training-tutorials/kde4-activities-fast-efficient-workflow/>
The KDE team view is here: <https://community.kde.org/KDE_Visual_Design_Group/Plasma_Activities>.
The KDE Handbook view is here: <https://docs.kde.org/stable5/en/plasma-desktop/plasma-desktop/activities-interface.html>