UPS assigns a tracking number to every shipment. Senders and recipients can use that unique number to track the package as it goes through the UPS delivery process.
UPS employees scan shipments at various points in the delivery process. UPS Web Tracking shows each of those scans and the estimated delivery date when the tracking number is entered on the UPS website's Tracking page.
UPS also offers the option to create a personal reference with any combination of numbers and letters up to 35 total characters. The Track by Reference section of the UPS Tracking page allows users to check the shipment's progress with this method.