India is launching a census¹ in which every person over the age of 15 will be photographed and fingerprinted² to create a biometric national database.

印度目前正在进行一项人口普查，所有超过15岁的人都将被采集肖像和指纹以建立一个国家级生物统计数据库。

India has a diverse population of a billion-plus people

The government will then use the information to issue identity cards.

Officials will spend a year classifying India's population of around 1.2 billion people according to gender³, religion, occupation and education.

This is India's 15th census（人口普查） , an exercise that has been carried out in the country every 10 years since 1872.

Over the next year, some 2.5 million census officials will visit households（家庭，家户） in more than 7,000 towns and 600,000 villages.

They will first begin the process of houselisting - which records information on homes. This count will, for the first time, also attempt to gather information on the use of the internet and the availability of drinking water and toilets in households.

The physical count of residents will take place from 9-28 February 2011.

The processes will stretch over 11 months, consume more than 11 million tonnes of paper, and cost 60bn rupees ($1.3bn; £880m).

India's Home Minister, P Chidambaram, described the process as "the biggest exercise... since humankind came into existence", according to the AFP news agency.

The national census is the only source of primary and credible⁴ data in India and is used not just to formulate⁵（规定，起草） government policies but also by private companies to identify markets for their products, says the BBC's Sanjoy Majumder in Delhi.

The first 16-digit identity numbers are due to be issued starting in November.

The full census results will be released in mid-2011.