The worldwide Jewish population experienced a marked decline during the 20th century due to the murder of six million Jewish people during the Holocaust, the genocide perpetrated by Nazi Germany and its allies during World War II. While there were almost 17 million Jewish people alive before the Holocaust, or the Shoah as it is known in Hebrew, after the war this was only around 11.5 million people. By using several different fertility scenarios, demographers have been able to reconstruct what the Jewish population would be in modern times if the genocide of Jewish people had not happened. In scenarios where there was a low or very low fertility rate, the Jewish population in 2000 would be in the range of 26 to 33 million people, double what it was in reality. In a scenario where the population growth rate was the same as that observed in the Jewish population after WWII, which was extremely low, the global Jewish population would have risen to over 20 million people.

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.

The Holocaust was the systematic extermination of Europe's Jewish population in the Second World War, during which time, up to six million Jews were murdered as part of Nazi Germany's "Final Solution to the Jewish Question". In the context of the Second World War, the term "Holocaust" is traditionally used to reference the genocide of Europe's Jews, although this coincided with the Nazi regime's genocide and ethnic cleansing of an additional eleven million people deemed "undesirable" due to their ethnicity, beliefs, disability or sexuality (among others). During the Holocaust, Poland's Jewish population suffered the largest number of fatalities, with approximately three million deaths. Additionally, at least one million Jews were murdered in the Soviet Union, while Hungary, Latvia, Lithuania, the Netherlands and Yugoslavia also lost the majority of their respective pre-war Jewish populations. The Holocaust in Poland In the interwar period, Europe's Jewish population was concentrated in the east, with roughly one third living in Poland; this can be traced back to the Middle Ages, when thousands of Jews flocked to Eastern Europe to escape persecution. At the outbreak of the Second World War, it is estimated that there were 3.4 million Jews living in Poland, which was approximately ten percent of the total population. Following the German invasion of Poland, Nazi authorities then segregated Jews in ghettos across most large towns and cities, and expanded their network of concentration camps throughout the country. In the ghettos, civilians were deprived of food, and hundreds of thousands died due to disease and starvation; while prison labor was implemented under extreme conditions in concentration camps to fuel the German war effort. In Poland, six extermination camps were also operational between December 1941 and January 1945, which saw the mass extermination of approximately 2.7 million people over the next three years (including many non-Poles, imported from other regions of Europe). While concentration camps housed prisoners of all backgrounds, extermination camps were purpose-built for the elimination of the Jewish race, and over 90% of their victims were Jewish. The majority of the victims in these extermination camps were executed by poison gas, although disease, starvation and overworking were also common causes of death. In addition to the camps and ghettos, SS death squads (Einsatzgruppen) and local collaborators also committed widespread atrocities across Eastern Europe. While the majority of these atrocities took place in the Balkan, Baltic and Soviet regions, they were still prevalent in Poland (particularly during the liquidation of the ghettos), and the Einsatzgruppen alone are estimated to have killed up to 1.3 million Jews throughout the Holocaust. By early 1945, Soviet forces had largely expelled the German armies from Poland and liberated the concentration and extermination camps; by this time, Poland had lost roughly ninety percent of its pre-war Jewish population, and suffered approximately three million further civilian and military deaths. By 1991, Poland's Jewish population was estimated to be just 15 thousand people, while there were fewer than two thousand Jews recorded as living in Poland in 2018.

Europe's Jewish population in 1939 was around 9.5 million people, and it is estimated that six million of these were ultimately killed by 1945. The persecution of German Jews escalated during the interwar period, particularly after Hitler's ascent to power in 1933, and again after Kristallnacht in 1938. However, the scale of this increased drastically following the German invasions of Poland in 1939 and the USSR in 1941, when Germany annexed regions with some of the largest Jewish populations in Europe. Extermination Camps As part of the "Final Solution to the Jewish Question", the Nazi occupiers established six extermination camps in present-day Poland; these were Auschwitz-Birkenau, Belzec, Chelmno, Majdanek***, Sobibor, and Treblinka. Prisoners, mostly Jews, were transported from all over Europe to these camps. Upon arrival, the majority of victims were sent directly to purpose-built chambers or vans, where they were murdered with carbon monoxide or Zyklon B gas. A relatively small number of prisoners were also forced to dispose of the victims' bodies, which often included their own family members, friends, or persons known to them. Most of the deceased were incinerated, and many of the camp records were destroyed; this means that precise figures for the number of deaths in extermination camps will never be known. It has been estimated that at least 2.7 million Jews were murdered in these six camps; over two thirds of these were killed at Auschwitz or Treblinka. Einsatzgruppen After extermination camps, the most common method of murder was through mass shootings. The majority of these shootings were not carried out by regular soldiers, but specialized task forces known as "Einsatzgruppen". Each group was just a few hundred men each, but they were responsible for some of the largest individual acts of genocide in the war. The largest of these took place at Babi Yar, near Kyiv in 1941, where almost 35,000 victims were beaten, humiliated, and then shot over a two day period. The Einsatzgruppen were most active in the annexed Soviet territories (although additional regiments were active in Poland and the Balkans), and their ranks were often bolstered by local volunteers. It has been estimated that Einsatzgruppen were responsible for the genocide of more than two million people in fewer than six years.

Jews were the dominant religious group in the Israel-Palestine region at the beginning of the first millennia CE, and are the dominant religious group there today, however, there was a period of almost 2,000 years where most of the world's Jews were displaced from their spiritual homeland. Antiquity to the 20th century Jewish hegemony in the region began changing after a series of revolts against Roman rule led to mass expulsions and emigration. Roman control saw severe persecution of Jewish and Christian populations, but this changed when the Byzantine Empire adopted Christianity as its official religion in the 4th century. Christianity then dominated until the 7th century, when the Rashidun Caliphate (the first to succeed Muhammad) took control of the Levant. Control of region split between Christians and Muslims intermittently between the 11th and 13th centuries during the Crusades, although the population remained overwhelmingly Muslim. Zionism until today Through the Paris Peace Conference, the British took control of Palestine in 1920. The Jewish population began growing through the Zionist Movement after the 1880s, which sought to establish a Jewish state in Palestine. Rising anti-Semitism in Europe accelerated this in the interwar period, and in the aftermath of the Holocaust, many European Jews chose to leave the continent. The United Nations tried facilitating the foundation of separate Jewish and Arab states, yet neither side was willing to concede territory, leading to a civil war and a joint invasion from seven Arab states. Yet the Jews maintained control of their territory and took large parts of the proposed Arab territory, forming the Jewish-majority state of Israel in 1948, and acheiving a ceasefire the following year. Over 750,000 Palestinians were displaced as a result of this conflict, while most Jews from the Arab eventually fled to Israel. Since this time, Israel has become one of the richest and advanced countries in the world, however, Palestine has been under Israeli military occupation since the 1960s and there are large disparities in living standards between the two regions.

In 2020, the names "Oświęcim/Auschwitz" were associated primarily with the place of martyrdom of the Polish nation (43 percent), and slightly less frequently with the extermination of the Jews (38 percent). During the observed period, it can be seen that more people associated this place with the Holocaust of Jews. However, one percent of respondents did not have any knowledge about Auschwitz in 2020.

In 2020, around 28.8 percent of the global population were identified as Christian. Around 25.6 percent of the global population identify as Muslims, followed by 14.9 percent of global populations as Hindu. The number of Muslims increased by 347 million, when compared to 2010 data, more than all other religions combined.

This statistic displays public perceptions and awareness of holocaust denial, in the European Union in 2018. As findings show, the majority of the respondents thought that denying the genocide of the Jewish people is a problem in their country, with Sweden and France having the highest share, at 79 percent and 78 percent of respondents respectively.

In 2024, the United Kingdom was the country where the highest number of anti-Semitic violent attacks, reaching 201. The second highest was recorded in Germany. However, it should be noted that the quality of reporting of anti-Semitic incidents varies greatly from country to country.

Islam is the major religion in many African countries, especially in the north of the continent. In Comoros, Libya, Western Sahara, at least 99 percent of the population was Muslim as of 202. These were the highest percentages on the continent. However, also in many other African nations, the majority of the population was Muslim. In Egypt, for instance, Islam was the religion of 79 percent of the people. Islam and other religions in Africa Africa accounts for an important share of the world’s Muslim population. As of 2019, 16 percent of the Muslims worldwide lived in Sub-Saharan Africa, while 20 percent of them lived in the Middle East and North Africa (MENA) region. Together with Christianity, Islam is the most common religious affiliation in Africa, followed by several traditional African religions. Although to a smaller extent, numerous other religions are practiced on the continent: these include Judaism, the Baha’i Faith, Hinduism, and Buddhism. Number of Muslims worldwide Islam is one of the most widespread religions in the world. There are approximately 1.9 billion Muslims globally, with the largest Muslim communities living in the Asia-Pacific region. Specifically, Indonesia hosts the highest number of Muslims worldwide, amounting to over 200 million, followed by India, Pakistan, and Bangladesh. Islam is also present in Europe and America. The largest Islamic communities in Europe are in France (5.72 million), Germany (4.95 million), and the United Kingdom (4.13 million). In the United States, there is an estimated number of around 3.45 million Muslims.