A river basin is the area of land covered by a river and its tributaries. The region drained by the Amazon River and its tributaries is known as the Amazon River Basin. Because it is home to the tropical rainforest, the Amazon is extraordinarily biodiverse. The Amazon River is home to 10% of the world's biodiversity.

While often used interchangeably, the two refer to different geographic entities. The Amazon River is the physical body of water—the main "artery" that flows roughly 4,000 miles from the Andes to the Atlantic. It is the world's largest river by discharge, carrying 20% of the Earth's freshwater. The Amazon Basin, however, is the entire drainage area (roughly 2.7 million square miles) where all rain and snow melt eventually flows into the Amazon River and its tributaries. It covers about 40% of South America, spanning eight countries. Think of the river as a single pipe and the basin as the massive funnel that feeds it. In 2026, protecting the "Basin" is critical because it includes the entire rainforest ecosystem, not just the water itself, which acts as a vital "carbon sink" for the global climate.