Permissions allow you to control who has access to your content files
& at what level. For example, you will want to retain read &
write permissions (along with the others) to your files - but you will
want to limit your 'viewers' access to 'Read only'.
Permissions are used to prevent the wrong people from doing the wrong things with your files. Including hackers.
Every Unix file has a set of permissions associated with it that specify who is allowed to use that file and in what way.
There are three kinds of permissions: