Different DVD types????????????

Recently purchased a new Dell xps desktop system that came with a DVD that reads/writes to dvd's or dc's. Can someone explain to me the different types of dvd's/cd's that are available and when to use each one(-R,+R,-RW,+RW). Thanks

This will talk about the brands.
http://www.digitalfaq.com/media/dvdmedia.htm

Now as to what format, + or - R, verify what format your euipment will use.
My stand alone dvd player for my tv only uses +R

RW's I refuse to use as I have lost to many, I.E., went bad, for them to be cost effective.

And have a look at this site:

http://www.dvddemystified.com/dvdfaq.html

JCurtis--I am sure this info is somewhere in SuperSparks link, but it may be a good summary of the differences
http://www.videohelp.com/dvd
In summary, the + and - versions are different and often incompatible formats which accomplish more or less the same end result. (Like Betamax/VHS or BlueRay/HDDVD--the latter by the way are missing from my link and one will probably eventually displace existing DVD).
The situation with -/+ is a little simpler in that many recorders and players now record/play both, but you have to check before buying the player/recorder.
RW means the disk can be erased and reused.