Defining Owner, Group, and Others (and Sometimes Everyone)
In the most basic file sharing, you set permissions for three user categories: Owner, Group, and Others. (There’s also Everyone, which is similar to Others.) You can use the Owner, Group, and Others categories to restrict access to a certain set of users, provide different levels of access to different users, or prevent access. When you create shared folders (called share points), Mountain Lion Server assigns default permissions to these three classes of users. Owners get read and write permissions, and Groups and Other get read-only.
These user categories are hierarchical; a user gets the permissions of the highest level to which he or she is a member. So, if a user is both the owner and in a group, the user gets the read and write permissions of the owner, not the lesser permissions of the group.
You can change the default permissions for a Group and Others to give them read and write permissions. In more complicated setups, you can also set different permissions for each individual user. This is described in the section “Working with Access Control Lists.”
But first, here’s a little more about the user categories.
The owner can be a user with a local account or one with a directory domain account. By default, the owner of a file or folder is the user who created it. The owner could also be the administrator.
The owner usually has the highest level of permissions: the ability to do anything to a file, such as edit, ...