What do you understand by the so called Totalization of social security? Discuss in the light of India–US Bilateral Totalisation Agreement (BTA).

Hint:
Totalization agreements are international social security agreements that help benefit rights of workers by eliminating dual social security taxation, both in the home country and the country where an employee works.
India had signed totalisation agreements with several countries; recent one with USA, which will help in preventing loss of nearly $25 billion every year lost by India. Also, Indian officials working in US will get full benefit by contributing to the provident funds in India rather than social security contribution to the US.