Scene: Meeting at work
Me: I don't know what I'm doing with the plone site but I got a new document up there and I even made it visible so you all could see it before the meeting. So what's the difference between visible and published?
Manager: Publishing it makes it visible to all users. Visible makes it visible to site admins. That's why [other employee] couldn't access it.
Me (to [other employee]): Oops, sorry! That was my fault, I don't know what I'm doing.
Manager: Although he had never logged in so I had to set up his account. And when I set up all of the developers, I made everyone site admins.
Me (to [other employee]): So that wasn't my fault - I clearly know what I'm doing!