The Plus Minus Blues

So a friend of mine went to the store and tried to buy a DVD burner. The guy behind the counter says will that be a DVD+R/DVD+RW or a DVD-R/DVD-RW with CD-R/CD-RW or CD+R/CD+RW compatability.

what is all this plus minus stuff. I have never noticed any pluses or minuses when I have bought media (I thought the minus was just a dash), and have no idea what they are talking about. Can someone point me to a site or give me the skinny here?

I felt like a complete idiot when I couldn't answer him.

 

Hey I can't thank you enough I did a search while I waited for an answer , and found nothing so this really does help quite a bit.

I appreciate the help!!