When a group is created, you can fully control its privacy. There are three different access levels:
Open: For groups where everyone can see the group and join. The group will appear in search results and all its content (for example, photos, videos, and discussions) is visible to anyone who views the group.
Closed: For closed groups, everyone can see the name and description of a group, but only group members can see the group's content.
Secret: These groups cannot be found in searches, and non-members cannot see anything about the group, including its name and member list. The group name will not be shown on members’ profiles.
Group administrators can change these options at any time by clicking on “Settings.”