A rainforest is a forest characterized by high rainfall, with annual rainfall in the case of tropical rainforests between 250 and 450 centimetres (98 and 177 in), and definitions varying by region for temperate rainforests. The monsoon trough, alternatively known as the intertropical convergence zone, plays a significant role in creating the climatic conditions necessary for the Earth's tropical rainforests.Rainforests are home to an incredible diversity of plants and animals. Scientists have estimated that there may be 30 million different kinds of insects alone in a single rainforest. Tropical rainforests are among the most threatened ecosystems in the world. They are being destroyed at an alarming rate.Between 60 and 80 percent of all the plant and animal species in the world live in tropical rainforests. Many of these species are found nowhere else on Earth. As rainforests disappear, so does the incredible diversity of life that they support.