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 behavior
A quick and automatic way to measure your customer behavior is with Repeat Customer Insights. It'll automatically import your Shopify data and run a number of analyses to highlight different customer behavior.