Which continent do you live in? • 你来自哪个大洲？ • На каком континенте вы живете?

Globally, the 20th century was marked by: (a) two devastating World Wars; (b) the Great Depression of the 1930s; (c) the end of vast colonial empires; (d) rapid advances in science and technology; (e) the Cold War between the Western alliance and the Warsaw Pact nations; (f) a sharp rise in living standards in North America, Europe, and Japan; (g) increased concerns about environmental degradation including deforestation, energy and water shortages, declining biological diversity, and air pollution; and (h) the ultimate emergence of the US as the only world superpower. The planet's population continues to expand at a fast rate: from 1 billion in 1820 to 2 billion in 1930, 3 billion in 1960, 4 billion in 1974, 5 billion in 1987, 6 billion in 1999, 7 billion in 2012, and 8 billion in 2022. For the 21st century, the continued exponential growth in science and technology raises both hopes (e.g., advances in medicine and agriculture) and fears (e.g., development of even more lethal weapons of war).

most-spoken language: English 18.8%, Mandarin Chinese 13.8%, Hindi 7.5%, Spanish 6.9%, French 3.4%, Arabic 3.4%, Bengali 3.4%, Russian 3.2%, Portuguese 3.2%, Urdu 2.9% (2022 est.)

most-spoken first language: Mandarin Chinese 12.3%, Spanish 6%, English 5.1%, Arabic 5.1%, Hindi 3.5%, Bengali 3.3%, Portuguese 3%, Russian 2.1%, Japanese 1.7%, Punjabi, Western 1.3%, Javanese 1.1% (2018 est.)

note 1: the six UN languages -- Arabic, Chinese (Mandarin), English, French, Russian, and Spanish (Castilian) -- are the mother tongue or second language of about 49.6% of the world's population (2022), and are the official languages in more than half the states in the world; some 400 languages have more than a million first-language speakers (2018)

note 2: all told, there are estimated to be 7,168 living languages spoken in the world (2023); approximately 80% of these languages are spoken by fewer than 100,000 people; about 150 languages are spoken by fewer than 10 people; communities that are isolated in mountainous regions often develop multiple languages -- Papua New Guinea, for example, boasts about 840 separate languages (2018)

note 3: approximately 2,300 languages are spoken in Asia; 2,140, in Africa; 1,310 in the Pacific; 1,060 in the Americas; and 290 in Europe (2020).