This document summarizes several different ecosystems. It describes biodiversity as the variation of life across genetics, species, and ecosystems. It then defines ecosystems as biological communities that interact with their physical environments. Several terrestrial ecosystems are outlined, including tropical rainforests, savannas, deserts, tundra, and deciduous forests. Details are provided on the climates and features of each. Marine ecosystems are also summarized, noting they cover most of the Earth and include oceans, coastal areas, and deep sea environments.