Poverty is a serious challenge in India, with approximately 27 crore (270 million) people living in poverty according to 2011-12 estimates. This represents about one fourth of the Indian population and constitutes the largest concentration of poverty in the world. Poverty is measured using indicators like income, consumption, literacy levels, health, access to resources, and is analyzed through concepts like the poverty line and vulnerability. There are also large disparities in poverty levels between states, with Bihar, Orissa, Madhya Pradesh, Uttar Pradesh having significantly higher rates than the national average.