The Department of Posts functioning under the brand name India Post , is a government

Government of India

The Government of India, officially known as the Union Government, and also known as the Central Government, was established by the Constitution of India, and is the governing authority of the union of 28 states and seven union territories, collectively called the Republic of India...

 operated postal system in India

India

India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

; it is generally referred to within India as "the post office".

The Indian Postal Service, with 155,333 post office

Post office

A post office is a facility forming part of a postal system for the posting, receipt, sorting, handling, transmission or delivery of mail.Post offices offer mail-related services such as post office boxes, postage and packaging supplies...

s, is the most widely distributed post office system in the world.
The large numbers are a result of a long tradition of many disparate postal systems which were unified in the Indian Union post-Independence.