Answer:
The code on the package
Explanation:
There is a code on every package that is sent out for delivery, this code is scanned at every milestone in the journey, with that you know where your package has gotten to.
The Postal Service is committed to providing customers with real-time visibility and control of their mail and package delivery services. The Postal Service’s goal is to scan all barcoded mailpieces (flats, letters, and packages) that enter the mailstream and track those items with additional scans up to the point of delivery. Scanning accuracy is critically important to the success of real-time visibility.
