How does Magento achieve multi-domain checkout in one single cart?

Question

One of the great features of Magento is the ability to have several domains but with the ability to have the shopping cart contents consistent across each website. Thus reducing the need for customers to repeat the checkout process for each domain.

My question is how is this achieved from a programmer's point of view? How is the session/cookie/whatever it is able to work across different domains?

Thank you

Answer 1

From what I understand they put a little bit of code on the end of the URL when you jump from domain to domain telling you what your session ID is so that it can copy the information over to the new cookie that you are using.