Unix/Linux permissions can be a confusing thing. I have seen a large number of posts asking about permisisons, so I hope that this
might go some way to assisting folks to understand what they are and how they work.

The basic unix permissions come in three flavors;

Owner Permissions : These are permissions that you have on your own files or 
directories.

Group Permissions : These are permissions that you and anyone in your group have on 
the file files or directories.

Other Permissions : These are permissions that other people have on your files or 
directories if not you, or in your group

filename.php   username   usergroup   rwx   r-x   r-x

If you notice, I have intentionally spaced out the permissions section, I have grouped the 9 characters into 3 sets of 3. This separation is key to how the permissions system works.