I'll give this one a try.

Let's say you are purchasing something online.
You come to a page with a form to fill out with your name,
address, city, state, zip code, and credit card number.
At the bottom of the page is a next/preview order button.
The next page brings up a summary of your order to review.
At the bottom of this page is a button to submit the order.
Clicking on that submit button posts the order to the server.
After you click the submit button you get a page saying something
like, "Your order is being submitted", and then you get a
page saying "Your order has been submitted. Thank you for business."

Remember, the previous page submitted your order.
So if you try to go back and the page re-submits
your order, you have now ordered something twice.

Your web browser doesn't know what kind of data was sent.
So it is asking you, "Are you really sure you want to do this?"
If you were making an online purchase you probably don't.
If you were doing an online search and what was being
submitted was only some search terms then no problem.
But since your browser doesn't know, it stops and asks.

Hope this helps some.

Pooh Bear

No wonder I keep winding up with double orders! I thought Amazon was trying to rip me off...

Thanks Pooh...

Jane

I hope you don't mind but I used your question
in a lesson about server-side programming.
The lesson was recieved very well.
Your question helped a lot of people.

Thanks. (from them too)

Pooh Bear