Customer classes allow you to segregate your customer base for easier data entry, reporting, and update. You should have at least one customer class set up, and every customer should be assigned to a class.
When you’re adding a new customer, you can merely add that customer to a Customer Class, and that new customer will inherit all of the default values from the Customer Class. You can overwrite any of the default values in the new customer record if you want.
Most reporting in Dynamics GP allows you to select data based on the Customer Class.
If you need to update a field value for every customer in a class, you can just make the change in the Customer Class, and then roll down the change to all customers assigned to that class.
Take a look at this video: