Assume that anything you post on the net anywhere is public. That used to be a good rule but various sites have lulled us into a false sense of security by providing function that gives you the illusion that you can post to a select group of people and nobody else will ever be able to see it. There are numerous problems with that. The interfaces are properly confusing, so it's really easy to post something to public that you thought was private and limited. It's often hard to go back and change permissions afterwards. Connected apps often ask for way more permission than they need. And the big one. You may find that the visibility is changed retrospectively by the platform provider.
This was brought home to me today by a couple of things on Facebook. I'm not going to rant about Facebook, and I'm not going to leave because I find it useful. But I am going to try and live by that rule again.
Assume that anything you post on the net anywhere is public.25 Musley Ln, Ware, Hertfordshire SG12 7
https://www.facebook.com/help/contact.php?show_form=data_requests
The classic problem is the teenage-early adult one. Why shouldn't you post a photo of yourself getting seriously mashed up to the other people who were there. Just as long as potential employers, parents, people in authority never see it. Ever.
There are plenty of other similar scenarios in the same vein. It's about limiting access to some aspects of your life and being sure that they stay limited.