PIN (Postal Index Number) Code was basically formed with an objective to simplify the sorting of mails and hence speed up the process of mail transportation and ultimate delivery.  This system was first introduced to India on August 15, 1972.

It was developed basically to allot specific number to each area, to avoid confusion and such that every area is identified with a unique six-digit number and also making sure that there is no duplication of numbers or names.  What has been achieved out of this is that an accurate delivery system, even while there were addresses to locate an area, confusion and duplication was not eradicated, especially with similar sounding names of areas, and it is here that PIN Code was crucial to identifying the correct location/area.

There are approximately 25,000 pin codes covering more than six lakhs villages and cities in India.  For each pin code, there is one main post office and many subpost offices.  The employee who delivers the mails to the respective addresses under that post office is called as Postmaster/Postman.

Today, usage of pin code http://www.onefivenine.com/india/head/map has become vital to communication and logistics, as it is not only the Postal Department but host of other services including but not limited to private courier services who fully depend on the pin code numbers.  In fact, numerous websites works as ready reckoner to get the information on pincode/area/state/city by just using one of the aforementioned information (by using pincode we can locate the area/village/city/state and vice versa) and exact geographical location http://www.onefivenine.com/india/head/pincodes of the post office/area.  You can search the village/city/area and get the correct pin code.

The uniqueness of this 6-digit number is that each number represents specific information about, like the first digit represents the State, the second digit represents the City, third digit represents the Village/District, and lastly fourth, fifth, & sixth digit represents the individual post offices.

India is further divided in zones to make segregation of mails easier, divided in eight zones, namely 2 Northern Zones, the first one consists of states like Delhi, Haryana, Punjab, Himachal Pradesh, and Jammu & Kashmir, and the second Northern Zone consists of states like Uttar Pradesh and Uttaranchal.  Likewise, two Western Zones, first consists of states like Rajasthan and Gujarat, the second consists of Chhattisgarh, Maharashtra, and Madhya Pradesh.  Two Southern Zones, first consisting of Andhra Pradesh and Karnataka, the second consisting of Kerala and Tamil Nadu and, lastly, two Eastern Zones, the first zone includes states like West Bengal, Orissa and North Eastern regions, and the second zone includes states like Bihar and Jharkhand.