What do you understand by drain of Indian wealth during the colonial period?

What do you understand by drain of Indian wealth during the colonial period?

The Britishers exploited India in every possible way. Raw material from India was exported are reduced price and expensive finished goods were imported to India. Also, the heavy administrative costs related to running of the colonial rule in India, in the form of wages and salaries of the administrative staff, and the expenses borne by Britishers in fighting wars were borne by revenues generated in India. All this led to a drain of India’s wealth.