Inventory management systems have evolved from manual stock tracking methods to modern computerized systems using barcodes and RFID. They allow retailers to track product sales and inventory levels in order to reorder supplies as needed. Early systems involved writing down purchases and estimates, while modern barcode and RFID technologies allow automatic scanning and tracking of inventory. Improvements in computing power and the development of technologies like barcodes, lasers, and RFID have enabled more advanced inventory management systems that provide retailers valuable sales data and help ensure adequate stock levels.