I understand that cookies are used to hold the information of what items has been added to a users shopping cart on the server side.
But then what happens when the user clicks "Buy" - how is the data from the server (i.e. the amount) transferred to the payment mechanism, which is probably a third party like WorldPay or something?

Thanks.

try a Google search .

0 members found this post helpful.

Try a better answer.

Most ALL of everything that's asked on LQ can be answered by Google. I want the answer from a *human*.

I agree that searching on the internet can be difficult. One method is sessions and now you can google....
http://www.tizag.com/phpT/phpsessions.php

The payment processing company, WorldPay etc will probably be able to give you the information on how to interact with their payment processing mechanism.

(It is probably as simple as passing the total, reference number and a merchant ID to them.)

Ahh, but what exactly do you mean by "passing"? How is that done?

Try being a bit less pushy.....

Here's how to get the BEST help from a place like LQ:
1. Do your own basic research, including Googling.
2. Post questions in which you state what you have found and then request help with interpretation or understanding.

It IS perfectly OK to just plunk down the question here, but then you have to expect that someone will tell you to "Go Google".

The other bit of advice is to ask more specific questions. When I first saw: "How does E-commerce work?" I was tempted to reply with:
"Quite well!"
If I wanted to be slightly less flip, I could have said: "It uses the Internet."

1 members found this post helpful.

See my previous post...the payment processing company you choose to use will be able to give you information on how to use the payment gateway with the data you gather (shopping cart data) from your site.