Customer
A customer resource instance represents a customer account with the shop. Customer accounts store contact information for the customer, saving logged-in customers the trouble of having to provide it at every checkout. For security reasons, the customer resource instance does not store credit card information. Customers will always have to provide this information at checkout.
The customer resource instance also stores some additional information about the customer for the benefit of the shop owner, including: the number of orders, the amount of money s/he has spent and number of orders s/he has made throughout his/her history with the shop as well as the shop owner's notes and tags for the customer.