One of the little used, and understood, features of Magento is customer groups. Many online businesses need to provide special pricing or other considerations for groups of customers. Magento, by default, creates groups for the most common intentions such as the following:
General: These are consumers who have registered with your site, either separately or as part of the checkout process.
NOT LOGGED IN: As the name suggests, these are customers visiting your site who are not logged into their customer account (and who may not have an account established yet).
Retailer: A customer who is buying products from you as a reseller. You are the wholesaler or distributor, and the customer is making the final sale to the end consumer.
Wholesale: Someone who buys from you to resell to other vendors.