The Point of Sale System (POS) or point of purchase is the time and place where a retail transaction is completed.
At the point of sale, the merchant calculates the amount owed by the customer, indicates that amount,
may prepare an invoice for the customer, and indicates the options for the customer to make payment.

A retail point of sale system typically includes a cash register (which in recent times comprises a computer, monitor, cash drawer, receipt printer, customer display and a barcode scanner) and the majority of retail POS systems also include a debit/credit card reader.