An online store where you can order and pay for a product or service. Carts are programs that run on a web server and usually come with an administration interface accessed through a web browser. Some carts are free, some cost many thousands. Most shopping cart programs are websites in themselves, so matching the cart's appearance to your current website is very difficult of not impossible. Some carts are able to be integrated into a current website and can "inject" the product displays and order processing forms into normal web pages.