Humans have been living on the continent of Australia (name derived from "Terra Australis"; Latin for "the southern land") for approximately 65,000 years, however population growth was relatively slow until the nineteenth century. Europeans had made some contact with Australia as early as 1606, however there was no significant attempt at settlement until the late eighteenth century. By 1800, the population of Australia was approximately 350,000 people, and the majority of these were Indigenous Australians. As colonization progressed the number of ethnic Europeans increased while the Australian Aboriginal population was decimated through conflict, smallpox and other diseases, with some communities being exterminated completely, such as Aboriginal Tasmanians. Mass migration from Britain and China After the loss of its American colonies in the 1780s, the British Empire looked to other parts of the globe to expand its sphere of influence. In Australia, the first colonies were established in Sydney, Tasmania and Western Australia. Many of these were penal colonies which became home to approximately 164,000 British and Irish convicts who were transported to Australia between 1788 and 1868. As the decades progressed, expansion into the interior intensified, and the entire country was claimed by Britain in 1826. Inland colonization led to further conflict between European settlers and indigenous Australians, which cost the lives of thousands of natives. Inward expansion also saw the discovery of many natural resources, and most notably led to the gold rushes of the 1850s, which attracted substantial numbers of Chinese migrants to Australia. This mass migration from non-European countries eventually led to some restrictive policies being introduced, culminating with the White Australia Policy of 1901, which cemented ethnic-European dominance in Australian politics and society. These policies were not retracted until the second half of the 1900s. Independent Australia Australia changed its status to a British dominion in 1901, and eventually became independent in 1931. Despite this, Australia has remained a part of the British Commonwealth, and Australian forces (ANZAC) fought with the British and their Allies in both World Wars, and were instrumental in campaigns such as Gallipoli in WWI, and the South West Pacific Theater in WWII. The aftermath of both wars had a significant impact on the Australian population, with approximately 90 thousand deaths in both world wars combined, as well as 15 thousand deaths as a result of the Spanish flu pandemic following WWI, although Australia experienced a significant baby boom following the Second World War. In the past fifty years, Australia has promoted immigration from all over the world, and now has one of the strongest economies and highest living standards in the world, with a population that has grown to over 25 million people in 2020.

In Australia, the crude birth rate in 1800 was 45 births per thousand people, meaning that 4.5 percent of the population had been born in that year. In the first half of the nineteenth century, Australia's crude birth rate decreased gradually, reaching just under 36 in 1850, however it then increased again over the next fifteen years, as the gold rushes brought many immigrants to the continent. After this, the crude birth rate dropped gradually until the Second World War, after the war Australia experienced another baby boom, reaching it's peak of 23 children per thousand in 1955. In the late 1970s the rate dropped rather sharply, falling from around twenty in 1970 to 15.8 in 1980, and since then the birth rate has decreased at a slower rate, and has fallen below thirteen births per thousand people in 2020.

Chart and table of population level and growth rate for the Sydney, Australia metro area from 1950 to 2025.

Chart and table of population level and growth rate for the Brisbane, Australia metro area from 1950 to 2025.

While the European colonization and settlement of other world regions largely began in the 16th and 17th centuries, it was not until the 19th century when the largest waves of migration began to take place. In early years, migration rates were comparatively low; in all of the Americas, the slave population actually outnumbered that of Europeans for most of the given period. Then, with the development of steam ships, intercontinental travel became more affordable and accessible to the masses, and voluntary migration from Europe rose significantly. Additionally, larger numbers of Asian migrants, especially from India and China, migrated to Australia, the Caribbean, and U.S. from the mid-1800s; although the U.S. and Australia both introduced policies that limited or prevented Asian immigration throughout most of the early 1900s. International migration between 1913 and 1950 was also comparatively low due to the tumultuous nature of the period, which involved both World Wars and the Great Depression.

The earliest point where scientists can make reasonable estimates for the population of global regions is around 10,000 years before the Common Era (or 12,000 years ago). Estimates suggest that Asia has consistently been the most populated continent, and the least populated continent has generally been Oceania (although it was more heavily populated than areas such as North America in very early years). Population growth was very slow, but an increase can be observed between most of the given time periods. There were, however, dips in population due to pandemics, the most notable of these being the impact of plague in Eurasia in the 14th century, and the impact of European contact with the indigenous populations of the Americas after 1492, where it took almost four centuries for the population of Latin America to return to its pre-1500 level. The world's population first reached one billion people in 1803, which also coincided with a spike in population growth, due to the onset of the demographic transition. This wave of growth first spread across the most industrially developed countries in the 19th century, and the correlation between demographic development and industrial or economic maturity continued until today, with Africa being the final major region to begin its transition in the late-1900s.

Life expectancy in Australia was just below 35 in the year 1870, and over the course of the next 150 years, it is expected to have increased to 83.2 by the year 2020. Although life expectancy has generally increased throughout Australia's history, there were several times where the rate deviated from its previous trajectory. the most noticeable changes were between 1890 and 1920. This period included Australia's Independence movement, the implementation of the 'White Australia' policy, the First World War and Spanish Flu epidemic, all of which impacted the demographics of Australia.

The fertility rate of a country is the average number of children that women from that country will have throughout their reproductive years. In 1800, Australian women of childbearing age would go on to have approximately 6.5 children on average over the course of their lifetime, and this number decreased gradually to just below five in the early 1850s. Over the next ten years the fertility rate increased to 5.7 children per woman, as an influx of migrants arrived on the continent during the Australian gold rushes, however the fertility rate dropped from 1860 until 1935, when it was then just 2.2 children per woman, although there was a small baby boom after the First World War. Australia's fertility rate did rise during the global 'Baby Boom' after the Second World War, reaching 3.4 in the 1960s, but it then dropped to two children per woman in 1980, and it has plateaued just under this number until today.