tar and '-p' option

[Lance Hoffmeyer <lance@augustmail.com>]

When backing up directories do I need the -p
option to save file attributes, ownership...
or do I use -p during restore to do this, OR
do I not need -p and it is done by default?

I don't really understand this option and I
want to make sure that if I have to recover
a filesystem that when I untar everything is
not set with the root permissions and ownership.

Lance