To some of our readers, this is plain basic but to readers who are just starting to learn Unix/Linux, knowing what the cryptic numbers beside each file name means is new. In my freshman computing class, most students are not familiar with Unix systems so this is foreign to them but I make it a point to explain it. PolishLinux.org explains what these numbers beside the file names mean and how to set/modify it.

To my students, now you have practically NO reason to say that you did not know who owned it nor if the file is executable or not! :P