Shopping cart abandonment is when a potential customer starts a check out process for an online order but drops out of the process before completing the purchase. Any item that enters the shopping cart but never makes it through the transaction is considered to be “abandoned” by the shopper. Shopping cart abandonment is an important aspect of the online shopping process that retailers pay careful attention to.
Shopping cart abandonment rate is calculated by dividing the total number of completed transactions by the total number of transactions that were initiated. This rate will identify what percentage of a site’s users signal purchase intent by adding an item to the cart, but don’t complete the purchase. The shopping cart abandonment rate is an important metric for e-commerce sites to keep track of because a high abandonment rate could signal a poor user experience or broken sales funnel. Reducing shopping cart abandonment leads directly to more sales and revenue, so optimizing the checkout flow a core area of focus for many online retailers.
source