Question

what is the purpose of using pin code in letters

Answer 1

A postal code (also known locally in various English-speaking countries throughout the world as a postcode, post code, Eircode, PIN Code or ZIP Code) is a series of letters or digits or both, sometimes including spaces or punctuation, included in a postal address for the purpose of sorting mail.

In February 2005, 117 of the 190 member countries of the Universal Postal Union had postal code systems.

Although postal codes are usually assigned to geographical areas, special codes are sometimes assigned to individual addresses or to institutions that receive large volumes of mail, such as government agencies and large commercial companies. One example is the French CEDEX system.

Answer 2

it is because if you mistakely put put the area location and all wrong the pincode help us to find the correct location