One example which I can give is suppose you create two sets of customer groups, say Customer group A1 for domestic sales and Customer group A2 for international sales. You can choose to give discount to customer group A1 which arecustomers in the domestic market by creating a pricing condition for group A1. Customer groups can be created in SAP SD usign the following menu path:
IMG >> Sales & Distribution >> Master Data >> Business Partners >> Customers >> Sales >> Define Customer Groups
Alternatively, one can use the transaction code OVS9. One needs to simply define a two digit alphanumeric customer group key. Once defined, the same can be assigned to a customer master record using the transaction code VD02. Such custoomer master key can be made mandatory for all customer master records.