At the beginning of the 19th century, the area of modern-day Italy, at the time a collection of various states and kingdoms, was estimated to have a population of nineteen million, a figure which would grow steadily throughout the century, and by the establishment of the Kingdom of Italy in 1861, the population would rise to just over 26 million.

Italy’s population would see its first major disruption during the First World War, as Italy would join the Allied Forces in their fight against Austria-Hungary and Germany. In the First World War, Italy’s population would largely stagnate at 36 million, only climbing again following the end of the war in 1920. While Italy would also play a prominent role in the Second World War, as the National Fascist Party-led country would fight alongside Germany against the Allies, Italian fatalities from the war would not represent a significant percentage of Italy’s population compared to other European countries in the conflict. As a result, Italy would exit the Second World War with a population of just over 45 million.

From this point onwards the Italian economy started to recover from the war, and eventually boomed, leading to increased employment and standards of living, which facilitated steady population growth until the mid-1980s, when falling fertility and birth rates would cause growth to largely cease. From this point onward, the Italian population would remain at just over 57 million, until the 2000s when it began growing again due to an influx of migrants, peaking in 2017 at just over 60 million people. In the late 2010s, however, the Italian population began declining again, as immigration slowed and the economy weakened. As a result, in 2020, Italy is estimated to have fallen to a population of 59 million.

Throughout the early modern period, the largest city in Italy was Naples. The middle ages saw many metropolitan areas along the Mediterranean grow to become the largest in Europe, as they developed into meeting ports for merchants travelling between the three continents. Italy, throughout this time, was not a unified country, but rather a collection of smaller states that had many cultural similarities, and political control of these cities regularly shifted over the given period. Across this time, the population of each city generally grew between each century, but a series of plague outbreaks in the 1600s devastated the populations of Italy's metropolitan areas, which can be observed here. Naples At the beginning of the 1500s, the Kingdom of Naples was taken under the control of the Spanish crown, where its capital grew to become the largest city in the newly-expanding Spanish Empire. Prosperity then grew in the 16th and 17th centuries, before the city's international importance declined in the 18th century. There is also a noticeable dip in Naples' population size between 1600 and 1700, due to an outbreak of plague in 1656 that almost halved the population. Today, Naples is just the third largest city in Italy, behind Rome and Milan. Rome Over 2,000 years ago, Rome became the first city in the world to have a population of more than one million people, and in 2021, it was Italy's largest city with a population of 2.8 million; however it did go through a period of great decline in the middle ages. After the Fall of the Western Roman Empire in 476CE, Rome's population dropped rapidly, below 100,000 inhabitants in 500CE. 1,000 years later, Rome was an important city in Europe as it was the seat of the Catholic Church, and it had a powerful banking sector, but its population was just 55,000 people as it did not have the same appeal for merchants or migrants held by the other port cities. A series of reforms by the Papacy in the late-1500s then saw significant improvements to infrastructure, housing, and sanitation, and living standards rose greatly. Over the following centuries, the Papacy consolidated its power in the center of the Italian peninsula, which brought stability to the region, and the city of Rome became a cultural center. Across this period, Rome's population grew almost three times larger, which was the highest level of growth of these cities.

The statistic depicts the median age in Italy from 1950 to 2100. The median age of a population is an index that divides the population into two equal groups: half of the population is older than the median age and the other half younger. In 2020, the median age of Italy's population was 46.4 years.

The population of Cistus albidus of Lake Garda (N-Italy), present at the northernmost margin of its range, is endangered by urban development and extreme climate events. Since this species has been continuously declining for over 200 years, conservation actions are necessary to prevent its extinction. To identify the best sites for an assisted colonisation of the species in the area, we carried out experiments posing 120 plantlets grown from seeds from the natural population in each of 5 sites within a 20 km range from the natural population. Environmental, demographic and meteorological parameters were monitored for 8 years at each site to evaluate the response to our intervention. Demographic changes occurred at different rates, reflecting the effect of environmental factors on new plants establishment and survival; the final survival rate of reintroduced plants was 45.3%. Unlike winter temperature, summer drought had a strong negative impact on plant survival. Inter-population comparison suggests a formerly wider distribution of the species, and bodes well for the survival of the newly created populations. Differentiating between ecological factors influencing growth and those regulating reproductive biology and success of new generations will help to improve long-term fitness and viability in assisted colonisation projects.

Albania, then known as Rumelia, was a province of the Ottoman Empire from the fifteenth century until it declared it's independence in 1912. Following a series of unsuccessful uprisings and brief occupations from nearby Serbia and Greece, Albania finally claimed its independence on November 28, 1912; however the Conference of London in 1913 then set the borders of the former-Ottoman states in Southern Europe, which left many ethnic Albanians living in other neighboring states, particularly Serbia (and what is now Kosovo). The newly-formed Albanian state collapsed in the wake of the First World War, and was controlled in parts by Greece, Italy and Serbia. The Paris Conference then established an independent Albanian state, which led to a period of political and economic turmoil that lasted until Italy's annexation of the region in 1939, during the Second World War. It is estimated that just under 3 percent of Albania's population perished as a direct result of the war, as Albania became the main theater for the Axis Powers' war against Greece. Italy then surrendered control of the area to Germany in 1943, and after the war ended in 1945, Albania became a Yugoslav satellite state and remained behind the Iron Curtain until it's collapse in the 1990s. Steady growth during the communist era From the war's end onwards, Albania's population enjoyed steady growth and almost tripled by 1990. Throughout this time, Albania underwent a series of political allegiances; first as a Yugoslav and then Soviet satellite states, but then became an important actor in the Sino-Soviet split, eventually siding with China in the 1960s. Gradually, Albania transitioned into a more isolationist and independent country in in the 1970s, and slowly adopted some more democratic practices. The total population surpassed two million people in the late 1960s, and three million in the late 1980s, but then a dramatic change in population growth occurred in the 1990s, as communism in Europe came to an end. Immediate decline following communism's end Increased freedom of movement, improved access to contraception and major lifestyle changes caused the population to fall into decline. The population did increase in the late 90s, despite a civil war in the first half of 1997 (in which over 2 thousand people died) sparked by a failure of the financial system in Albania. The Albanian Army was also involved in the war in neighboring Kosovo between 1998 and 1999. The 2000s brought about further decline, and the population is just 2.9 million in 2020, a decline of approximately 400,000 people in thirty years. Albania has been a candidate for accession to the EU since 2014, and membership would bring further change to the country.

The world's Jewish population has had a complex and tumultuous history over the past millennia, regularly dealing with persecution, pogroms, and even genocide. The legacy of expulsion and persecution of Jews, including bans on land ownership, meant that Jewish communities disproportionately lived in urban areas, working as artisans or traders, and often lived in their own settlements separate to the rest of the urban population. This separation contributed to the impression that events such as pandemics, famines, or economic shocks did not affect Jews as much as other populations, and such factors came to form the basis of the mistrust and stereotypes of wealth (characterized as greed) that have made up anti-Semitic rhetoric for centuries. Development since the Middle Ages The concentration of Jewish populations across the world has shifted across different centuries. In the Middle Ages, the largest Jewish populations were found in Palestine and the wider Levant region, with other sizeable populations in present-day France, Italy, and Spain. Later, however, the Jewish disapora became increasingly concentrated in Eastern Europe after waves of pogroms in the west saw Jewish communities move eastward. Poland in particular was often considered a refuge for Jews from the late-Middle Ages until the 18th century, when it was then partitioned between Austria, Prussia, and Russia, and persecution increased. Push factors such as major pogroms in the Russian Empire in the 19th century and growing oppression in the west during the interwar period then saw many Jews migrate to the United States in search of opportunity.

In 1800, the population of modern day Algeria was estimated to be around 2.5 million people, and by the turn of the twentieth century it had almost doubled to five million. In the first three decades of the nineteenth century, Algeria was a semi-autonomous province of the Ottoman Empire, however an invasion by France in 1830 was the beginning of 130 years of French rule, and the development of Algeria's modern borders by 1875 (although northern Algeria was treated as an extension of the French metropole, with elected representatives in the Assembly). Although the rest of the century saw both medicinal and economic progress, French rule also dismantled traditional Algerian political and societal structures, as well as the oppression of Islam, particularly in rural areas. Algeria in the early 1900s The first few decades of the twentieth century saw increasing Algerian and Islamic influence in local government. Throughout both World Wars, Algerian soldiers played an integral part in the French military, and were responsible for Algeria's liberation from Nazi Germany, as well as decisive campaigns in Italy and France. Although Algerian troops often made up the first wave of soldiers to go into battle, they did not receive the same treatment or pay as their French counterparts, and Algerian veterans did not receive the same rights as French veterans until 2017. As Europe's control over its colonies weakened in the mid-1900s, independence movements in countries such as Algeria gained momentum, and the Algerian War of Independence was one of the most violent and arduous during this time. Although it began as guerilla warfare in 1952, a series of massacres and reprisals led to all-out war in 1955, between the National Liberation Front (FLN) and the French-Algerian government. Up to one million Algerian's lost their lives in the war, and approximately twenty percent of the Muslim population became refugees. The war ended in March 1962, through the Evian Accords, and Algeria's independence was acknowledged on July 3, 1962. Independent Algeria In the aftermath of the war, there was a mass exodus of ethnic Europeans, as well as the systematic genocide of thousands of pro-French Algerians who remained in the country. Much of Algeria's agriculture had been destroyed, it's economy was left without structure as the majority of those in positions of power returned to Europe, and seventy percent of the workforce was unemployed. Relative peace followed and the country slowly modernized over the next three decades, however military rule failed to sufficiently stabilize the country, and the government's attempts to suppress Islam's influence in politics eventually led to a civil war in 1992. The civil war involved different factions with Islamic and pro-government agendas, and was very regionalized. The high number of massacres eventually led to splits within all paramilitary factions, which the government then capitalized on to re-establish control, and the war effectively ended in 2002. Since then, the military's control over Algerian politics has gradually decreased, and Algeria has become more peaceful and democratic (however they have not had an elected President since April 2019). Increased stability has also allowed the population to grow exponentially, and today it is almost 44 million people, double what it was in the mid-1980s.

A global phenomenon, known as the demographic transition, has seen life expectancy from birth increase rapidly over the past two centuries. In pre-industrial societies, the average life expectancy was around 24 years, and it is believed that this was the case throughout most of history, and in all regions. The demographic transition then began in the industrial societies of Europe, North America, and the West Pacific around the turn of the 19th century, and life expectancy rose accordingly. Latin America was the next region to follow, before Africa and most Asian populations saw their life expectancy rise throughout the 20th century.

There were 30 288 400 Instagram users in Italy in January 2024, which accounted for 50.9% of its entire population. The majority of them were women - 53.8%. People aged 25 to 34 were the largest user group (7 300 000). The highest difference between men and women occurs within people aged 18 to 24, where women lead by 3 200 000.