Write permissions

[-=seth=-]

whats the difference between applying recursively and not applying recursively, what i pressume they meant is dont apply repeatedly through out the subfolder but /config is a subfolder?

Write permissions on folders (do not apply recursively/to subfolders):
/config
/tools/smarty/compile
Write permissions on folders and subfolders/recursively:
/img
/mails
/modules
/themes/prestashop/lang
/translations

if i put the wrong write permissions here will i be exposing myself to security breaches in the future

thanks for your help
Seth