Short answers, pulled from the story.
The Amazon rainforest covers most of the Amazon basin, a basin that spans 7 million square kilometers, of which 6 million square kilometers are forest. It holds an estimated 390 billion individual trees across about 16,000 species and represents over half of the remaining rainforest on Earth.
The Amazon rainforest spans nine nations. The majority sits in Brazil, followed by Peru and Colombia, with smaller amounts in Bolivia, Ecuador, French Guiana, Guyana, Suriname, and Venezuela. Four nations use Amazonas as the name of a first-level administrative region.
The name Amazon arose from a war Francisco de Orellana fought with the Tapuyas and other tribes, in which the women fought alongside the men. Orellana drew the name from the Amazons of Greek mythology described by Herodotus and Diodorus.
Recent anthropological findings suggest the Amazon was densely populated before European contact. Some 5 million people may have lived there in AD 1500, and one estimate based on food production projections suggests over 8 million people in 1492, before disease from Europe such as smallpox devastated these societies.
The Amazon holds one in ten known species in the world, the largest collection of living plants and animal species anywhere. Scientists have classified at least 40,000 plant species, 2,200 fishes, 1,294 birds, 427 mammals, 428 amphibians, and 378 reptiles, and the region holds about 2.5 million insect species.
Research suggests that once deforestation reaches about 20 to 25%, a tipping point would flip eastern, southern, and central Amazonia into degraded savannah over decades. By 2022 about 20% had already been deforested and a further 6% was highly degraded.
No. The claim that the Amazon produces more than a quarter of the Earth's oxygen is a misused statistic that actually refers to oxygen turnover. The net contribution of the ecosystem is approximately zero, and in 2021 it was reported that the Amazon emitted more greenhouse gases than it absorbed for the first time.