Look toward the upper right hand corner of envelopes and packages mailed through the United States Postal Service, or USPS, and you will see a melange of stamps and print outs for the scanners and readers. This is referred to as the postmark and zip code. Together this comprises the postal data matrix. Each piece of the matrix represents something, such as the five digit ZIP code. ZIP stands for Zone Improvement Plan. The ZIP code is used to help make mail delivery more efficient.
Pick up a mailed envelope or package and look at the upper right hand corner. Look for a stamp or series of stamps. The value of the stamp will be the number along with a dollar or cent sign next to it. Some mailings use postage meters. If no stamp is present, look for an imprint with a dollar or cent value indicating the amount needed to mail the envelope or package.
Look at the stamp or imprint. Look for a date stamp. This date is the postmark and indicates the first date the piece of mail entered the United States Postal Service system.
Examine the postmark and stamp imprint. Look for a series of five numbers in a row. This is the origin ZIP code. Read this ZIP code and use a ZIP code directory to locate the area from where the mail was sent.
Look for a series of lines running over the stamp or postage imprint. The USPS places these lines over the stamps to cancel or prevent secondary and fraudulent use of the stamps. Postage is for one delivery only.