Freshwater is water that contains very little salt, unlike the salty water found in oceans. Rivers, lakes, ponds, and most streams contain freshwater. The water you drink, the water in your school's fountains, and the water flowing from your kitchen tap are all freshwater (even though it's been cleaned and treated first).

Only about 3% of Earth's water is freshwater, and most of that is frozen in glaciers and ice caps. The small amount that remains as liquid freshwater is incredibly important because nearly all land animals, including humans, need it to survive. We can't drink ocean water because the salt would make us sick.

Scientists and environmentalists often use freshwater as an adjective to describe things associated with non-salty water environments. A freshwater fish, like a trout or bass, lives in rivers or lakes rather than in the ocean. Freshwater ecosystems include all the plants, animals, and microorganisms living in and around rivers, lakes, and wetlands.

This word helps us distinguish between two fundamentally different types of water on our planet. When you're reading about nature or science, knowing whether something involves freshwater or saltwater immediately tells you a lot about where it is and what lives there.