A customer is a person or organization that has purchased from your store.
It is important to separate them from people who have not purchased yet. While you might treat them the same, they are merely prospective customers and cannot be measured as customers yet.
The vast majority of ecommerce customers are one-time customers who have only one order, while the rest are returning customers or repeat customers.
Eric Davis
Analyze your customer's behaviors before they defect
Your customers aren't yours forever. Some might have defected today, never to be seen again.
You need to analyze your customer behavior so you can reach them before they defect.