A tropical rainforest is a forest of tall trees in a part of the world that is warm all year round. A rainforest has an average of 50 to 260 inches of rain falls yearly.

Rainforests belong to the tropical wet climate group. The temperature in a rain forest rarely gets higher than 93 °F (34 °C) or drops below 68 °F (20 °C). It’s average humidity is between 77% and 88%. Almost all rain forests lie near the equator.

Today rainforests cover less than two per cent of the earth’s surface, but it is estimated that more than half of all of the world's plant and animal species live in tropical rainforests. Tropical rainforests produce forty per cent of Earth's oxygen.

 There are more kinds of trees in a rainforest than any other area of the world. In studying the South American rainforests, scientists have counted about 100 to 300 species in one 2 1/2-acre area. Seventy percent of the plants in the rainforest are trees.

About one fourth of all the medicines we use come from rainforest plants. More than 1,400 varieties of tropical plants are thought to be potential cures for cancer.

All tropical rainforests resemble one another in some ways. Many of the trees have straight trunks that don't branch out for 100 feet or more. Trees do not grow many branches below the canopy, the second layer of the rainforest, because there is little light. The majority of the trees have smooth, thin bark because there is no need to protect the them from water loss and freezing temperatures. Because the trees are so similar, many can only be identified by their flowers.

Although similar in many ways, the three largest rainforests--the American, the African, and the Asian--have a different group of animal and plant species.