An ecosystem is a community of living organisms interacting with each other and their physical environment.

A food web shows the complex network of feeding relationships in an ecosystem.

Biodiversity refers to the variety of life forms in a given ecosystem, region, or the entire planet.

The greenhouse effect is the warming of Earth due to gases trapping heat in the atmosphere.

A keystone species has a disproportionately large effect on its ecosystem relative to its abundance.

Ecological succession is the natural process of change in the composition and structure of an ecosystem over time.

Carrying capacity is the maximum number of individuals an environment can support sustainably.

Abiotic factors are non-living components of an environment, like sunlight, temperature, and water.

The water cycle is the continuous movement of water on, above, and below Earth's surface.