KDE Plasma is a fantastic desktop environment. It is popular for its feature set that allows a user to customize the experience, add widgets, and multiply the usefulness of the desktop with various elements.
When you get started, you already have certain widgets in place to access things. You can customize/remove them or add some more pre-installed ones. In either case, you can also download widgets from the KDE store and try them out.
Here, I mention some of my favorite picks among the default, pre-installed, and downloadable widgets.
I was messing with the sticky notes widget the other day. I wanted to see how many can I add to the panel, so I spam clicked it 5 times and it froze the entire plasmashell.
I had to manually edit the plasma config file to remove them or else plasmashell just never worked.
After fixing plasmashell, I tried to add 1 sticky note again, and plasmashell froze again. So I just never touched it ever after.