Customer Users
Customer access to your account is supported if you have enabled the Customer Access option on the Web Presence subtab at Setup > Company > Setup Tasks > Enable Features. If this feature is disabled, Customer records do not include an Access subtab. For more information, see Giving Customers Access.
You can give customers access by checking the Give Access box on the Access subtab of the Customer record. You can assign one role per customer, usually the Customer Center role, or your customized version of it. You also can grant access to individual customer contacts based on their email addresses.