A customer is anyone who visits your store.  A person does not have to purchase something to be called a "customer," though we hope they do!

A customer account is automatically created the first time a user places an order in your storefront. Customer accounts can be viewed on the Search Customers page in your store's Administration Area. Each customer account must have a unique email address.

When checking out, the customer may optionally enter a password. If they do, the customer will be able to log into the Customer Account Area in the storefront to view their order history, edit their contact information, etc.

Customers that don't enter a password will be given the option to do so the next time they place an order in the storefront.

Customers can also be affiliates.