Anybody know what the toggle switch indicating public is on the upper right side of posts is?

Is it for making post public or private and if so what does it mean? You can only see it? Or is there more to this?

Just noticed this…

This page is a permanent link to the reply below and its nested replies. See all post replies »

Confined · 56-60, M

When you click on Forums, then common forums, if non public it wont show up.
How ever if you look at All Forums it does. Not sure what use that is.