The software allows online shopping customers to "place" items in the cart. Upon "checkout" the software calculates a total for the order including shipping and handling (i.e. postage and packing) and taxes, if applicable.

Technical definition

These applications typically provide a means of capturing a client's credit card information, but they rely on the software module of the secure gateway provider, in conjunction with the secure payment gateway, in order to conduct secure credit card transactions online.

Some setup must be done in the HTML code of the website, and the shopping cart software must be installed on the server which hosts the site, or on the secure server which accepts sensitive ordering information. E-shopping carts are usually implemented using HTTP cookies or query strings. In most server based implementations however, data related to the shopping cart is kept in the Session object and is accessed and manipulated on the fly, as the user selects different items from the cart. Later at the process of commit, the information is accessed and an order is generated against the selected item thus clearing the shopping cart.

Cart software can be generally categorized into two categories. Download-and-install: this is most often associated with a one-time fee, although there are many free products available as well.

Hosted service: from a hosted service provider and is generally paid for on a monthly/annual basis; also known as the application service provider (ASP) software model. This model often has predefined templates that a user can choose from to customize their look and feel. Colors can be chosen as well as logos etc. In some cases getting your estore going is as simple as picking a few colors, uploading pictures of the items you are selling and typing in the descriptions.

Some of the top hosted shopping cart providers are OS Commerce, Zen Cart, Joomla Cart, 3dcart, Volusion and Monstercommerce & 1ShoppingCart.