Profile comments?

[BassTractor]

This may not be a site issue, what do I know, but:

Today, the Notifications icon said I had a Comment. Never seen such a thing before.
Now, I could read it, and could comment it, but have no idea what this is about.
It seems to be the same as a Profile Comment.

Where does one comment? Have not seen any link on any profile.
How can one comment?
What are comments for?
Who can see them?


Thanks,
Bert