All new customers are automatically logged in the customer list. See an individual customer’s full history of appointments by either searching for their name/email in the appointments list or by sorting the appointments list by client name or email.
Notice there’s the "import" button just above the list. By uploading the list of your existing clients, you’ll make sure that, when they come back, duplicate logs won’t be created for them (as long as they provide the same info as both name and email).
You can also export the list as a .csv .
Custom Fields - get all the info you want from customers.