What Is a Postal Code?

A postal code, also known as a post code, PIN code, or ZIP code, is a series of letters and/or numbers included in a mailing address. These codes are used by postal services to sort mail.

Postal codes are written on mail and packages as a part of the street address. They are used for mail sorting in 117 countries around the world. The codes are generally assigned to specific geographical areas but can also be assigned to individual institutions that receive a large amount of mail.

Different countries have different systems of postal codes; for example, the U.S. system uses five primary numbers and an additional four digits occasionally used for more specific sorting. The UK uses both numbers and letters in four- to seven-character codes.