Demography founded

What are the foundations of demography?
Population's main ingredients are basically the vital statistics: births, marriages/fertility and deaths.
Fundamentals of Demography will oblige the reader to understand the elementariness of populations and how they impact on the day to day lives of everyone in whichever continent globally..
Who proposed the demographic?
The theory of demographic transition or of population stages or of population cycle has many versions.
It has been propounded by W.S.
Thomson and F.W.
Notestein.
They explain the theory in three stages..

What are the foundations of demography?