What's the difference between a forest and a tropical rainforest?

What is a tropical rainforest? How is it different from what we think of as a regular forest? First of all, a regular forest usually consists of one dominant species of tree - the evergreen forests of colder climates, or the redwood forest of California, for example. A tropical rainforest has many species of trees and plants, and trees of the same species very seldom grow close together. Scientists have counted as many as 300 different species growing in one 2 1/2 acre (one hectare) in a South American rainforest. While forests are found in all climates and all parts of the world, tropical rainforests are found only in hot, humid climates. They cover less than six percent of the Earth's land surface. Most are found in areas near the equator such as Central America, South America, Africa, and Southeast Asia. A rainforest often gets more than 100 inches of rain a year, the average humidity is between 77 and 88 percent, and the temperature is usually between 93