Typically the central part of a city develops as an employment hub leaving the outskirts (formally known as suburbs) as residences. However in the case of India most metropolis are actually creating new employment in suburbs e.g. - Gurgaon and Noida on the outskirts of Delhi. Ideally everyone wants to stay close to their place of work however as we know manufacturing/heavy industries should be constructed away from residences.

(1) Definition and explanation of demographics- http://bit.ly/2VQvhao

(2) Urban Demographics- http://bit.ly/2UGm2wO