whats with this visudo thing?

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http://crunchbanglinux.org – Everyone says that you need to use this to edit your sudoers file, but I have never used it in all the years I have used sudo. Every time I install sudo I just:su nano -w /etc/sudoersThen add my name with ALL=(ALL) ALL as I am on a single user system and this has never given me trouble. So why does everyone say you have to use visudo which according to bash isn't even on my machine?Edit: I know -w isn't needed for this in nano but I always use it (HowTos)