Most countries use a postal code system to deliver mails. In India, the Postal Index Number Scheme called PIN code was introduced on 15 August, 1972. PIN code is a system of numerical identification of a delivery post office. How does PIN help in timely delivery of mail? The PIN code digits from left to right progressively pinpoint and locate the geographical location of the post office. The first digit represents a region in the country and the second, a sub-region.