Have you ever wondered what scientists mean when they talk about an ecosystem? It starts with the world around us—our environment. The word itself comes from the old French term environer, which means “to surround, enclose, and encircle.” An environment is simply the collection of conditions that all living things exist and survive in.

At the heart of environmental science is the study of how these surroundings function. Think of an ecosystem as nature’s household, with its own residents (living parts), physical structure (non-living parts), an energy bill (energy flow), and a highly efficient recycling program (nutrient cycling). The official definition puts it this way:

The interaction and interrelationship between the living community (plants, animals, and organisms) in relation to each other and the non-living community (soil, air, and water) is referred to as an ecosystem.

In essence, an ecosystem is a community where living organisms and their physical surroundings are linked by two critical processes: the one-way flow of energy and the continuous cycling of nutrients.

So, what are the essential ingredients in nature’s household? Every ecosystem, from a desert to the deep sea, is built from the same two types of components.