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The shopping cart (or basket) is where the shopping and ordering process starts. The main components of a shopping cart using the abstraction APIs are described in this topic.

The cart APIs are built around the  IOrderRepository interface, which lets you load, update, save and eventually delete carts. The cart objects are represented by the ICart interface, which extends the IOrderGroup interface.

A main reason to prefer IOrderRepository over the concrete classes is that it is implementation-independent. Whether your underlying implementation is the legacy cart mode, or the new serializable one, IOrderRepository works the same, the providers do all the work "under the hood".

## Load and create a cart

Each cart is identified by its name, customer ID, and market. IOrderRepository has multiple overloads/extensions to create or load a cart. If a parameter is missing from the method call, the default value is used. For example, if you use overload without an MarketId parameter, the current market is used.

To load a cart, use the Load() method:

This loads the existing cart, and returns null if no cart exists.

To create a cart, use the .Create() method:

It is good practice to use the extension method .LoadOrCreate, which creates a cart (if none exists) or loads an existing cart:

## Add items to a cart

To add an item to a cart, you must first create an ILineItem. IOrderGroup has an extension method called CreateLineItem, which takes the SKU's code, and returns an ILineItem instance. A good practice is to check if the cart has an existing line item with the same SKU. If yes, increase the quantity. Otherwise, create a new line item and add it to a cart.

## Remove items from a cart

To remove an item from a cart, remove it from the shipment. Normally, a cart has only one shipment, so removing the first shipment is enough.

## Validate a cart

Before a customer can place an order, a cart must be validated to make sure it has enough quantity, that the prices are correct and up-to-date, and that any promotions are applied correctly.

## Save a cart

To save a cart, call IOrderRepository.Save on an instance of ICart orderRepository.Save(cart);.