You can use the Abandoned checkouts resource to retrieve a list and a count of abandoned checkouts. A checkout is considered abandoned after the customer has added contact information, but before the customer has completed their purchase.

This resource may be helpful to complete the following actions:

Gather marketing information on customers who have abandoned their cart.
Use information to remarket to abandoned checkout customers.
Understand customers’ behavior.
Track abandoned checkouts over time.
View abandoned checkout items.