By default ...
These are the default security settings. Security on an individual page can be changed by pressing the "Security" button while in the Edit area.
You can put users into different logical "groups". With user groups you can set fine-grained permission controls on the wiki. You can set the default permissions for a group above, and you can control the security of a particular page by going into the edit area and pressing the "Security" button.
Enter groups of users with one username per line (separated with returns).