There are three privacy settings for Facebook groups: open, closed and secret. If you want to know who can see your posts and your involvement with a particular group, it's important to understand the differences. The status of a group is shown by an icon displayed next to the group name on its front page. A padlock indicates a closed group, while a smaller padlock inside a gray circle indicates a secret group.
Who Can See the Group
Anyone on Facebook, existing group member or otherwise, can see the name of a closed group. Nonmembers can locate the group in search and click through to view its name and its list of current members. Secret groups, in contrast, are completely invisible to nonmembers -- they do not appear in search, in the news feed or anywhere else on Facebook unless you are currently a part of the group.
Who Can See the Group's Posts
The posts within both closed and secret groups cannot be viewed unless you are a current member, in contrast to open groups, where posts are visible to all. Click through to a closed group you're not a member of, and all you can see is the group name, its description and a list of current members. You cannot click through to a secret group at all, unless you're a member of it.
Who Can Join the Group
Any Facebook user can be added to a closed group by a friend who is a member of the group, although approval by the group admin is sometimes required. In addition, any user can message the admin of a closed group requesting permission to join the group. Membership in a secret group is only available through an invitation from a friend who is a member of the group. Secret groups are invisible, so there's no way for nonmembers to see the group or access the "Join group" button.
After you join either a closed or secret group, there's no difference in the way the group functions -- you can post, like and comment on threads without restriction. Your friends may see notifications about you joining a closed group in their news feeds, but they will not see stories relating to individual posts within it unless they are also members of the same group. In the case of secret groups, your friends will not see any news feed stories at all, unless they are also members of the same group.
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