The document discusses key concepts related to measuring national income in India such as GDP, NDP, NNP, and per capita income. It provides details on how the Central Statistical Organization of India estimates these aggregates using methods like product, income, and expenditure to measure economic activity at both current and constant prices. It also outlines the evolution of base years used in the national accounts statistics from 1948-49 to the latest base year of 1999-2000 in the new series of estimates.