A metaphor used in ecommerce sites selling products such as books or clothes. The user is able to navigate through catalog pages which describe the products on sale and can pick a product to buy, usually by clicking a button or entering some details on a form. This item is then added to the shopping cart. When the user wishes to complete their transactions they visit a checkout page which provides information on the items sold, their price, and postage rates. ecommerce site builder software almost invariably uses the shopping cart metaphor.