Why use a closed/secret group on Facebook?

The main benefit of using a 'closed' or 'secret' group on Facebook is that the posts and contents are visible only to those who are members and only members are able to write a post on the group page. The group posts/contents do not appear on the Facebook User's Timeline/Newsfeed to non-members. Members are limited and have to be approved by an Admin person before being added to the group. A Secret Group can not be found on a search on Facebook, its members are not visible to non members. It is totally hidden except to members. You can upload photos/videos and documents to the group that you do not wish to share with the whole of Facebook, just the group. You can also carry out a survey on the group page. Event - if you wish to hold an event i.e. a birthday party or a meeting, then you can post an 'Event' on the group page giving details of Date, Time etc. Unsuitable posts can be deleted by an Admin person.