When you place files on a UNIX system, you can assign the files various levels of permission, specifying who can access them, and what type of access they can have. The permission levels regarding who can access files are: owner (the person who created the files), group (such as a group of individuals specifically identified, or global (anyone). The type of access can be set to permit the users to read (look at the contents and copy it), write (edit or change the contents, rename and/or move the files), or execute (run a file as a UNIX program).