For those interested in, or using, Facebook, advice from the AV maker Sophos (found by accident) might be useful. I've been told that setting up the appropriate permissions and limits on a Facebook account can be a bit of a puzzle, so Sophos offers:

Facebook - Privacy settings recommended by Sophos

The above article embeds 5 links to other pages for details. In case you have a more specific need to know, the links are to:

Facebook - Profile privacy settings - Sophos recommends

Facebook - Search privacy settings - Sophos recommends

Facebook - Privacy settings for feeds - Sophos recommends

Facebook - Poke, message and friend request privacy settings - Sophos recommends

Facebook - Privacy setting for applications - Sophos recommends

The recommendations are an easy read, and include brief explanations of what each setting actually does, with some suggestion of non-obvious implications of what could happen if you change one; but it doesn't prohibit you from making your own decisions.

John