The 21st (twenty-first) century is the current century of the Anno Domini era or Common Era, in accordance with the Gregorian calendar. It began on January 1, 2001, and will end on December 31, 2100. It is the first century of the 3rd millennium. It is distinct from the century known as the 2000s which began on January 1, 2000 and will end on December 31, 2099.
The world population was about 6.1 billion at the start of the 21st century and reached 7.7 billion by January 2019. It is estimated to reach about 8.6 billion by the year 2030, and 9.8 billion by the year 2050. According to the United Nations World Urbanization prospects, 60% of the world's human population are projected to live in megacities and megalopolises by 2030, 70% by 2050, and 90% by 2080. By 2040, more than 5 times the current global gross domestic product are expected to be invested in urban infrastructure and its use. According to World Economic Forum, 65% of children entering primary school will end up in jobs or careers that currently do not yet exist.
The entire written works of mankind, from the beginning of recorded history to the 2003, in all known languages, is estimated to be at five exabytes of data. Since 2003, with the birth of social media and "user-generated content", the same amount data is created every two days. The advancement of the sum total of human knowledge and information continues to grow at an exponential rate; humans now collect and archive more data in one day than in the previous 10 years.
War and most kinds of crime and violence have declined considerably compared to the 20th century; such a period of "relative peace" between major powers has not been documented in human history since the Roman Empire.Poverty is still widespread globally, but fewer people live in the most extreme forms of poverty, relative to recorded history. In 1990 nearly 36 percent of the world's population lived in extreme poverty compared to only 10% in 2015.
Life expectancy continues to increase and child mortality continues to decline. A baby born in 2016 can on average (globally) expect to live 72 years; 26 years longer than the global average of someone born in 1950. Ten million Britons (16% of the population of the United Kingdom) are expected to live to 100 or older. However climate change remains an extremely serious concern; being described by UN Chief António Guterres as an "existential threat" to humanity.
Advances in technology such as ultrasound, prenatal genetic testing and genetic engineering is changing the demographics and has the potential to change the genetic makeup of the human population. Because of sex selective abortion, fewer girls have been born in the 21st century (and since 1990) compared to in past centuries, mostly because of son preference in East and South Asia. In 2014 only 47 percent of Indian births were of girls. This has led to an increase in bachelors in countries such as China and India. The first genetically modified children were born in November 2018 in China, beginning a new biological era for the human species and raising great controversy.
Anxiety and depression rates are rising in the United States and many other parts of the world. However, suicide rates have fallen in Europe and most of the rest of the world so far this century, declining 29% globally between 2000 and 2018, despite rising 18% in the United States in the same period. The decline in suicide has been most notable among Chinese and Indian women, the elderly and middle-aged Russian men.
Telecommunications in the early 21st century are much more advanced and universal than they were in the late 20th century. Only a few percent of the world's population were Internet users and cellular phone owners in the late 1990s; as of 2018 55% of the world's population is online and as of 2019 an estimated 67% own a cell phone. In the 2010s, artificial intelligence, mostly in the form of deep learning and machine learning became more prevalent, and is prominently used in Gmail and Google's search engine, as well as in banking, the military and other niches. In 2017, 14% of the world's population still lacked access to electricity.
There is a debate among experts and the general public on how to pronounce specific years of the 21st century in English. Regarding this, academics suggested that since former years such as 1805 and 1905 were commonly pronounced as "eighteen oh" or "nineteen oh" five, the year 2005 should naturally have been pronounced as "twenty oh-five". A less common variation would have been "twenty nought-five". Generally, the early years of the 21st century were pronounced as "two-thousand (and) five", with a change taking place in 2010, where pronunciations often shift between the early-year standard of "two-thousand and ten" and the common approach used in the late 20th century of "twenty-ten".
The Vancouver Olympics, which took place in 2010, was being officially referred to by Vancouver 2010 as "the twenty-ten Olympics". The latest timeframes for change are usually placed at 2020.
According to The Stanley Kubrick Archives, in the press release for his film 2001: A Space Odyssey, film director Stanley Kubrick included specific instructions for journalists to refer to the movie as "two thousand and one" instead of the commonplace pronunciation of "twenty-oh-one". Kubrick said he did this in the hope that if the film became popular, it would influence the pronunciation of that year.