ZIP code
Sign in to saveAlso known as ZIP+4 code, Zone Improvement Plan, zip code area
numeric postal code used in the United States and its territories
~28 min read
Encyclopedic overview
A 1974 postage stamp encouraging people to use the ZIP Code on letters and parcels
The ZIP Code system (an acronym for Zone Improvement Plan) is the system of postal codes used by the United States Postal Service (USPS). The term ZIP was chosen to suggest that the mail travels more efficiently and quickly (zipping along) when senders include the code in the postal address. ZIP+4 is a registered trademark of the United States Postal Service, which also registered ZIP Code as a service mark until 1997, and which claims "ZIP Code" as a trademark though it is not registered.
Excerpted from Wikipedia’s “ZIP code” article, available under the CC BY-SA 4.0 licence.