A USPS tracking number is a series of numerals allocated to individual parcels by the United States Postal Service to keep a record of where parcels are once they are shipped. A USPS tracking number consists of 22 numerals.
Tracking numbers used by USPS are displayed as five groups of four numerals each plus two numbers on the end. One example would be 9202 0021 3467 8765 3200 46. Tracking numbers are printed onto self-adhesive labels that also comprise a barcode.
Once the parcel with a tracking number has been accepted by USPS, the code is entered at each location on the parcel's journey from origin to destination. Parcels can be tracked by senders and recipients through the USPS online tracking service.