The difference between public, private and secret groups

A group has 3 levels of privacy, chosen when creating a group.  

The 3 levels are as follows: 

• Public: the group is then visible to everyone. The content is only visible by joining this group, through simple membership, without the group administrator's approval. 

• Private: the group is also visible to everyone. The member list and content are hidden; to access it, you must request to join the group.

• Secret: the group is invisible and does not appear to everyone on the site. It is only accessible by invitation.