Pin Code which we also call postal index number code. Postal index number (PIN number) or Pin Code is the 6 digits numeric code of the post office used by India Post.
The Indian Postal Service introduced the digit zip code, which we know as the Pin Code on 15 August 1962, to make the process of letters and parcels more efficient and easier.
The Pin Code is a 6 digit number as you are told. Each digit number has a specific meaning.
1 digit denotes the territory of India, 2 digits denote the sub-region of India, 3 digits denote the district and the last 3 numbers denote the post office code.
Thus the first 3(three)digits collectively denote the postal district while the last 3 digits designate the specific post office within the district.
India has 9 PIN areas, 8 of which are geographical areas, and 4 are reserved for the Army Postal Service.