PIN code stands for Postal Index Number code. Also known as Zip code or area postal code, Pin code is the post office numbering code system used by the postal service of India, India Post.
The PIN was first introduced in India on August 15, 1972. It is a 6 digits long code with each of the digits denoting a particular meaning.
The first three digits of the PIN represent a specific geographical region called a sorting district that is headquartered at the main post office of the largest city and is known as the sorting office. A state may have one or more sorting districts depending on the volumes of mail handled. The fourth digit represents the route on which a delivery office is located in the sorting district. The last two digits represent the delivery office within the sorting district starting from 01 which would be the GPO or HO.