Definition: A persistent shopping cart is a feature of an ecommerce store that retains products in a customer's shopping cart beyond one visit. Persistent shopping carts reduce cart abandonment by providing a consistent user experience that enables shoppers to pick up where they left off.
Persistent shopping carts support this tendency by allowing customers continue their shopping experience without having to search for a desired product upon their return. In addition, many purchases take place between multiple devices with customers researching on a mobile device prior to buying - or even completing the transaction from their phone or tablet. When logged in, persistent shopping carts follow a user across devices. Saving user sessions in any fashion improves their shopping experience by providing continuity.
Persistent shopping use long-term or "persistent" cookies. Unlike the short-term form that expires at the end of a session, persistent cookies stay on a user's browser after they leave a website.
Persistent cookies establish a specific code for a browser and device combination, and the shopper is then able to access the same products upon returning. Persistent cookies have an expiration that is set upon creation. Many online stores give their persistent cookies a thirty day window, allowing for users to return over a longer period of time (when they're especially susceptible to forgetting which products they added to cart). Persistent shopping carts depend on a user login, requiring customers to sign up before their shopping carts will be retained across multiple visits.
A related option for online merchants is to show customers their browsing history when they return. While not as granular as persistent shopping carts, this is still an effective method for pointing users to the products they were interested in.