Know PIN CODE history & meaning

Postal Index Number (PIN) or PIN Code is a 6 digit code of Post Office numbering used by India Post. The PIN was introduced on August 15, 1972. There are 9 PI​N regions in the country. The first 8 are geographical regions and the digit 9 is reserved for the Army Postal Service. The first digit indicates one of the regions. The first 2 digits together indicate the sub region or one of the postal circles. The first 3 digits together indicate a sorting / revenue district. The last 3 digits refer to the delivery Post Office.

The first digit of PIN indicates as below:

First Digit	Region	States Covered
1	Northern	Delhi, Haryana, Punjab, Himachal Pradesh and Jammu & Kashmir
2	Northern	Uttar Pradesh and Uttaranchal
3	Western	Rajasthan and Gujarat
4	Western	Maharashtra, Madhya Pradesh and Chhattisgarh
5	Southern	Andhra Pradesh and Karnataka
6	Southern	Kerala and Tamil Nadu
7	Eastern	West Bengal, Orissa and North Eastern
8	Eastern	Bihar and Jharkhand
9	APS	Army Postal Service

The first 2 digits of PIN indicates as below:

First 2 Digits of PIN	Circle
11	Delhi
12 and 13	Haryana
14 to 16	Punjab
17	Himachal Pradesh
18 to 19	Jammu & Kashmir
20 to 28	Uttar Pradesh and Uttaranchal
30 to 34	Rajasthan
36 to 39	Gujarat
40 to 44	Maharashtra
45 to 49	Madhya Pradesh and Chhattisgarh​
50 to 53	Andhra Pradesh
56 to 59	Karnataka
60 to 64	Tamil Nadu
67 to 69	Kerala
70 to 74	West Bengal
75 to 77	Orissa
78	Assam
79	North Eastern
80 to 85	Bihar and Jharkhand
90 to 99	Army Postal Service (APS)

source://www.indiapost.gov.in