A POS (Point of Sale) system is a combination of hardware and software used by businesses to complete sales transactions. It includes devices like cash registers, barcode scanners, and receipt printers, along with software to manage sales, inventory, and customer data. When a customer makes a purchase, the POS system records the transaction, updates inventory levels, and generates receipts. POS systems help businesses operate efficiently by streamlining the checkout process, reducing errors, and providing insights through reports. They are used in various industries like retail and hospitality to improve customer service and manage business operations more effectively.