population is the summation of all the organisms of the same group or species, who live in the same geographical area and have the capability of interbreeding. 

Indian Population is 1.237 billion in 2012

china 1.351 billion

USA  313.9 million

Indian current population is estimated to be 1.27 billions

Advantages:-

Advantages of population growth are...growing population can generate economic growth as it causes more demand for products and also leads to an increase in the human labor in the country.

more money as the business will thrive on the popularity.

In over populated countries there will be more inventions and construction to help deal with increasing population. more constructions ....more jobs ....better for the economy.

large no. of youth so working power is more,

Disadvantages:-

Disadvantages are...population growth without equal agricultural advancement brings food shortages, property shortage and also dependent.

Air borne diseases are caused by the over population

hunger, poverty, ecological destruction, pollution, political instability

lot of competition in water and food

unemployment

it can cause less supply of natural resources

more traffic .... more pollution

Over population can't be an advantage for any country . Specially for India where government is so corrupted . 
If the population is high in any country, the basic needs of the population ie. Food, Cloths, Shelter 
( forget about health facilities, education & others ) are not fulfilled . Over population, poverty , illiteracy , & other evils are joined together like a chain . High population is there , so less job opportunities, again joblessness so poverty , again poverty is there , so illiteracy . No one can separate them . 
Over population creates environmental problems like more pollution of air , water & noise . 
Still India could handle the situation in a human way if the leaders of the country were non-corrupted .Now in cities people are aware of over population , so hardly they have more children as they are educated . But India is made of thousands of thousands villages where people are still very poor , over population is there in the villages . So no question of education . Over population is a curse for India .

Advantages of Overpopulation i)Efficient utilization of resources A major portion of our country's resources are lying idle or are underutilized.We need more manpower to utilize them effectively so that there is no wastage. ii)Expansion of Market An increase in the total population will raise the demand for various essential as well as luxury goods.It will act as an incentive for the producers to set up more industries which will bring economic development. iii)Better Labor Force The growing population will help in increasing the national output of the country and we can have the benefits of new talented minds of the younger generations. iv)Greater Investments and Capital Formation The population will create a wider market.Hence it will attract the investors to invest on these items.This will lead to a net addition in the capital stock of the country. Disadvantages of Overpopulation i)Shortage of Food Grains With the increase in the population it becomes difficult to feed all the mouths properly as the agricultural sector of our country is still not mechanized.Also the increase in the population will put a greater stress on the land leading to its fragmentation. ii)Environmental Problems We are all aware about the various environmental problems that our country faces.Global Warming is one of them that results from heavy pollution from the industries. iii)Problem of Unemployment There will be a huge problem of unemployment and underemployment with the increase in the population as additional jobs created could not keep pace with the growth rate. iv)Poverty and Low Standard of Living Low level of per capita income reduces the purchasing power of the people making them poor.They cannot arrange for the proper education of the children resulting in the lower standard of living. v)Inflation It has been seen that prices of basic food items rises due to the increase in the population. Advantages of Underpopulation i)Greater Availability of Resources In an underpopulated country, per head availability of natural resources will be higher.Hence farmers will have a greater share in the land or the average holdings will be more. ii)Low rate of Pollution Urbanization and industrialization will be minimum if the population of the country is small.Hence there will be lower levels of pollution and ecological balance along with biodiversity will be maintained. iii)Availability of Government funds Government expenditure will reduce considerably and the government will be able to concentrate more on economic development.Also poor people will have a greater share in the funds and civic amenities. iv)Higher standard of living An underpopulated country will be able to utilize its resources effectively with the labor saving technology.Hence per capita income shall be higher which will raise the standard of living. Disadvantages of Underpopulation i)Inadequate Labor Force Insufficient labor forces will utilize the resources in a poor way.Country will also face shortage of labor for its developmental projects. ii)High Average Cost of Production The labor cost shall be more in an underpopulated country.This will raise the average cost of production.Hence the prices of goods will also be higher. iii)Production may be Constrained In an underpopulated country,production activities may depend on the immigration of the labor from other countries.Hence growth process may be hampered if the immigration is affected due to several factors. IT IS ON US TO DECIDE WHETHER THE HUGE POPULATION IS A BANE OR A BOON.HOWEVER THE PRESENT SCENARIO CLEARLY INDICATES THAT THE HUGE POPULATION OF INDIA IS A CURSE AND THE COUNTRY NEEDS TO TAKE IMMEDIATE STEPS TO CONTROL IT.