Absolute, Relative Population

The population growth has not been equal between  the large regions of the world. World's population is distributed this way:

80.75% in developing countries

19.25% in developed countries 

First of all, let's understand the difference between developing and developed countries. The developing country is a nation with low living standard,  high population growth, undeveloped industrial based and low resources to live. 

A developed country is a nation that is highly developed economically speaking and also advanced technological infrastructure. Birth rate is lower than others. 
Take a look at the map to identify which countries are in each category. 

Economic Development

Nowadays the world's population grows at a rate of 77 million people per year, highlighting six countries for its notable increase: India, China, Pakistan, Nigeria, Bangladesh and Indonesia. 

To study population we need to know its density, (relative population) which means how many people live per square kilometer . For this purpose,  the number of inhabitants (absolute or total population) is divided between the extensions where they live, in the following way:

Total Population/ Land extension (area)= Population density (inhab/km2)

For example, Mexico and the United States' extensions, our country is smaller, their population density are 50 and 31 respectively, as you can see, it all depends of the territory. Another example is China and India which are the highest in total population but their relative population (density) is not that high due to their high extension of territory.