As of 2010, the two countries that are exceeding 1 billion people are China and India. This are by far the two most populated countries in the world, combined, they make around 1/3 of the world's total population. Even with the law that forbid the Chinese to have more then one child, that lasted few decades, their number still managed to grow (mainly because the law was not so strict in the rural areas). India, on the other hand, has very big fertility rate, there's no laws that restrict the number of children a family can have, and with this rate it's just matter of time when will India take over the number one place, as the world's most populated country.