A Shopping Cart is a series of pages that are all linked together through some sort of programming (usually PERL or JavaScript) that allows data to be transferred along with the viewer as he or she moves from page to page. For example:

     A woman enters a site. That site sells clothing. One page displays the dresses the site has for sale. Another displays the shoes, and yet another displays the accessories.

     The woman clicks to purchase a dress. The purchase is then added to her "Shopping Cart". She then moves to the shoes page and clicks to purchase a pair. That item too is added to her Shopping Cart. Finally, she moves to the accessories page and adds a scarf. After choosing the items she wants to purchase, she clicks on the order page link and a page pops up listing all of her purchases with a final price added up. That's the concept of a Shopping Cart.

     It seems like a rather simple process on this side of the curtain, but behind the scenes, it's quite a difficult task to get that purchase data to move along from page to page as the viewer shops around.