I am Australian as you know. And we have currently roughly 23 million people. And I have noticed my main city slowly become more crowded in the peak times and I wished there was less people there. But I never really thought hard about it. Only thought hey maybe there are too many people here. But one day in 2010 an Australian called Dick Smith released a documentary called "Dick Smith's population puzzle". I bought it for $10 and watched it. And the TLDR of the documentary is "Australia is over populated and the government here is doing nothing about it". And after watching this documentary the only thing I could so is say wow. That man Dick Smith, he gets it in a way no one else in this country has before. To Dick Smith, an area or country being over populated is not simply having more people then a set number. Like over X people is over populated. He says this: 1. If the country does not have enough infrastructure like houses, roads, hospitals, schools, police, etc etc so all the people have access to these or 2. If the country does not have enough food to feed everyone or 3. If the country does not have enough water for the population or 4. The country does not have enough employment for the population etc etc Then the country is over populated. And by these standards Australia with it's small population is over populated, as we don't have enough water, food prices are ever increasing, the employment rates are falling, the hospital wait lists are ever increasing, you have to book your child in at birth to get a place at a good high school etc etc etc. And the government here does nothing about it. They only care about growth. More growth, more growth. And to sustain this growth in part they have huge amounts of immigration and natural births without increasing all the 4 points mentioned above ti cater for all these new people. If you liken it tot he stock market. Super high growth numbers can last forever. Eventually the market has to settle out or crash just like in 1929. And the total population of the world (and Australia to a point) in a graph is looking like the stock market just before 1929. Super high growth with to call for restraint. How does this matter to the rest of the world? This is relatively easy to see. I'll put a number of points I see as issues the world has. 1. Food. There are famines in the world, and in other places the food price is skyrocketing out of control. Africa is one easy to see example of this. But take a look in your local super market. Unless your super rich you'll notice it's harder each year to get a good shop for the same amount of money. Too many people and not enough food to go around so the price goes up. 2. Hospital waiting lists. Too many people and hot enough hospitals so the wait lists just get longer and longer. And not everyone can afford private health insurance because . . . . 3. of unemployment. Too many people and not enough jobs to go around. In an ideal word we would be training up people from our own countries and employing them. Not bringing in foreign workers who bring their families, and that's 2-3 at least more mouths to feed and have infrastructure for. 4. Water. Not just for drinking, for agriculture and business too. Clean water is a valuable scarce resource. Something many people of the world just do not have. 5. The economy. Most countries are obsessed with growth. And getting more and more people. But all these people need services. And it costs more money to provide the services to all these extra people. Money the governments simply do not have, so they have to do it on foreign debt. And too much debt and to get situations like Spain or Greece or the USA or Japan. Not good at all. Conclusion or TLDR My definition of over populated is not a set figure for a country or the world. My definition of over populated is when bringing more people in lowers the living standards drastically for everyone in the country/world then that country/world is over populated. And by this metric I believe many countries and the world as a whole is over populated. By a large margin. But what do you think? Is your country over populated in your eyes? Is the world over populated in your eyes? Do you have an opinion on this very important issue.