HDI measures a country's development according to metrics like life expectancy, education, and income. The author chose HDI as their project topic to learn about how to develop their country. India's 2020 HDI rank was 130 with a score of 0.646, indicating medium development. Key factors that affect India's HDI include low government spending on education, reduced schooling due to COVID-19, and lack of access to sanitation for many citizens. Studying HDI highlighted areas where India is lagging and can improve, such as infrastructure and public health.