I am a new member since a couple of weeks ago and have been reading some of the posts.  They are using abbreviations and I am not sure exactly what they stand for.  Is there a place to look them up that I haven't found yet?

They are RC, ARC, RWAP that I have noticed so far.  Thanks a lot for any help.

From the help desk- (HTH's) :D  ETA- I see RWAP isn't on this list.  RWAP or RWP= received with a problem ;)

Acronyms/Abbreviations common on PBS:

• TBR = To Be Read (click the "show description" button on the TBR Pile page to read the full description of its purpose. The TBR Pile is in the dropdown menu under Book Lists on the right-hand side of your account page)
• UnPosted books = books not currently available to order; these books may be added to your Wish List.
• Posted books = books currently available to order.
• WL = Wish List. See What is the Wish List? for more information.
• RL = Reminder List. This is a list of the books you are considering ordering in future. See What is the Reminder List? for more information.
• BIR = Books I've Read List. This is a list of all the books you have already read.
• FIFO = "first in, first out". FIFO refers to the order in which books are requested at PBS. See What is FIFO? for more information.
• ISBN = International Standard Book Number, usually found on the back or inside front flyleaf of a book.
• ARC = Advanced Reader Copy (aka Uncorrected Proof, Review Copy); a preview copy of a book sent to reviewers in advance of a book's release; not the final copy of a book, and not permitted for swapping at PBS.
• BoB = Box-O-Books. This service allows members to swap books without credits! See What is Box-O-Books? for more information about this feature.
• Boxer = member subscribed to Box-O-Books.
• PM = Personal Message. You can read your PMs in your Message Center, by clicking Personal Message on the right-hand side of your account page.
• BX = BookCrossing. BookCrossing.com is a website unaffiliated with PBS. BX books often have stamps or stickers on them, with their BX registration numbers.
• UBS = Used Book Store
• USPS = United States Postal Service
• PBS-DC = PBS Delivery Confirmation. See What is PBS Delivery Confirmation? for more information about this feature.
• FOL = Friends of the Library, an organization which runs sales of decirculated library books.
• BCE = Book Club Edition.  Book club editions are special printings of books that use cheaper materials and are slightly smaller in size than standard hardcovers. They're usually sent out via mail order book clubs, hence the name, and sometimes do not have ISBNS (if this is the case, they must be posted using the Post a Book without an ISBN feature).  They are permitted for swapping at PBS.
• R&R - Richard and Robert, co-Founders of the PaperBackSwap site

Acronyms/Abbreviations common on the Internet in general:

• LOL = Laughing Out Loud
• ROFL = Rolling On the Floor Laughing
• ROFLMAO = Rolling On the Floor Laughing My A** Off
• BTW = By The Way
• OTOH = On The Other Hand
• ETA = Edited to Add. Used mainly on a forum post that has been edited, to explain why the editing was done.
• OT = Off-Topic
• OP = Original Poster (or Original Post). Used mainly in Discussion Forums, to refer to the post that started the topic OR the person who started the topic.
• ISO = In Search Of
• AFAIK = As Far As I Know
• YMMV = Your Mileage May Vary
• IIRC = If I Recall Correctly
• NM = Never Mind
• KWIM = Know What I Mean?
• FWIW = For What It's Worth
• NP = No Problem
• BRB = Be Right Back
• HTH = Hope That (or "This") Helps
• TTFN = Ta-Ta For Now
• TTYL = Talk To You Later
• bump (as the lone word in a Forum post) = Bump Up My Post = empty post added to bring topic back to top of Forum topic list.  This is permissible in Book Bazaar topics once per day per topic.

Thanks.  Guess I hadn't looked far enough yet.  Some of them I have figured but a few had me stumped.

1. What are mass market paperbacks and how do they differ from regular paperbacks? 
2. Why are ISBN's different on the same book?  I have a book that is on the Club Wish List, but the ISBN number doesn't match.  I can see that one is a hardback and one is an audio, so I understand why they wouldn't match, but the paperbacks don't match either.
3.  I have also run across terms I don't understand.  In the forums, people talk about their DH or DS, etc., and from the context, I know it's their husband and son, but what does the D mean?

Mass market paperbacks are the smaller standard size paperbacks like you mostly find at grocery stores. Tradesize paperbacks are the larger ones that are basically the size of a hardback but softcover.  I don't know what those new taller but not tradesize paperbacks are called.

Some books come in many different editions with many different ISBNs.  The ISBN and binding have to match.  So if the ISBN brings up an audio and you have a hardback-or it brings up a paperback and you have a hardback-you have to post the book without an ISBN.  People expect to get the binding that's in the PBS listing. Sometimes publishers use the same ISBN for multiple bindings.

Sometimes books are reissued by other publishers who give them a whole new ISBN. 

Most books have a different ISBN for each binding-but not always. So make sure the ISBN and binding match.

The D means Dear  or Dumb depending on your mood when posting :-))

http://www.internetslang.com/  This site has a listing of commonly used internet slang,