What is this?  How does it work?  How do you sign up for it?

It's a method of sending and receiving money online -- https://www.paypal.com/

it's easy and almost imediate it takes a day or two I think to verfiy a bank account if you are going to link it to one, basicaly they deposit a dollar into your account and then request it back in order to verfiy that it is your account and is active.  BUT you do not have to link it to an account, I didn't for the first few months I had one, just funded it with sales from ebay, but later I found how easy and secure it is to use paypal vs entering bank info so I linked my checking account.  I use it all the time here at PBS and SwapaDVD, as well as anytime it's available on a web based purchase.

You can also print postage on Paypal - I never go to the post office any more because of this great service. You have to pay for DC on every book in order to use it, but it is worth it to me not to have to worry about getting to the PO in time to mail out my books. I have it set up so that the charges come directly out of my checking account.

I use PayPal for everything I buy on Ebay...either linked to my checking acct. or Mastercard.