IPN - Instant Payment Notification - A behind the scenes look

IPN is nothing but a methodology. Without delving into the geeky details, here's how it basically works:

1. Your visitor arrives at your web site.

2. He (she) is ecstatic about your e-Book

3. He wants it - and he wants it NOW!

4. He hits the "Buy" button.

5. He is taken to Paypal's web site

6. He pays the specified price

7. At the exact moment his credit card (or Paypal account) is being charged by Paypal, it also sends out a request to a "special" link on your web site - a.k.a the "IPN Notify Url". Let's just say that it looks like:
http://www.YourSite.com/paypalnotifylink.php

8. While making this request to the above link, it also sends out certain information about your buyer to this link, like Buyer name, address, amount paid, status of the payment (VERIFIED or FAILED), etc.

9. You, the seller, has already hired a geek like me to program this paypalnotify.php in such a way, that if the status of the payment was successful, the program then displays the link to download your eBook, or in a more secure fashion, your user is added to a database on your site, and the script also assigns them a "secret" username and password to access a "secure" password-protected area where he can finally download your precious e-Book (or HTML page, or PDF document, or zip file, etc).

10. It then sends your customer an email stating how and where to download your eBook, and also notifies you - the owner - of the purchase, by email.

11. The paypalnotify.php scripts then sends back a notification to Paypal that it has successfully completed executing, and hands control back to Paypal.

12. At this point, Paypal has completed the entire transaction, and then re-directs your buyer to your actual "return_url" that you have specified nakedly right on your sales page.

13. All this page does is inform the customer, that details about how to get his eager hands on your product, has already been emailed to him, and that he should now go check his email.

14. Your buyer checks his email, arrives at your "password-protected secure" url, enters the username/password specified in the email, and happily downloads the ebook.

15. End of story

Setting up IPN and IPN FAQ's