India launches what it calls world's biggest census India on Thursday kicked off what is says will be the world's biggest census that it hopes will help plug wastage in government welfare schemes, boost tax revenue and define consumers more clearly. WORLD More than two million census workers will cover an estimated 1.2 billion people, defining them in demographic, socio-cultural and economic terms, including such parameters as mobile phone and Internet usage and banking access. "Census 2011 is the largest exercise of its kind in human history. Our goal is to identify, count, record and issue identity cards to every Indian citizen," Home Minister Palaniappan Chidambaram said ahead of the launch. The census in the world's second-most populous country is held every 10 years. China, with a population of 1.3 billion, also has a census every 10 years. With about two-thirds of the Indian population in hard-to-reach rural areas, the census is the main source of data for everyone from manufacturers of cars and marketers of toothpaste to government officials planning and implementing key programs. Since the first census in 1872, it has also been key to drawing up constituencies for local and national elections. With the government stepping up the rollout of massive programs for the poor such as rural jobs and health insurance, the data should also help plug leakages, which a former prime minister once estimated at about 85 percent of the total outlay. The data will also help take the guesswork out of companies' investment and marketing plans in Asia's third largest economy. "For a large country like ours, any detail that you can get on the population is always useful," said Ajit Ranade, chief economist at Aditya Birla Group. "We just don't know enough." The government will also, for the first time, spend about 35 billion rupees ($786 million) on preparing a National Population Register (NPR), which will have photographs and fingerprints of all persons above the age of 15 years. The NPR will pave the way for the ambitious Unique Identification scheme, which aims at issuing a smart card and UID number to every Indian citizen, enabling easier access to banking, welfare payments and boost tax collections.