From Rainforest Alliance website: http://www.rainforest-alliance.org/kids/facts/tropical-forest
What is a Tropical Forest?
Today, most of the industrialized world senses little connection to the tropical forest, living in large, busy cities far away from these fertile ecological powerhouses. We forget that the forest regularly saves our global food supply by offering new, disease-resistant crops. We forget about the hundreds of billions of dollars worth of trade in tropical timber, non-timber forest products and forest-derived drugs. We forget about things that are ultimately beyond value: the livelihoods of millions of forest peoples, a stable and livable climate for us all, the existence of most of our fellow species, and simple things we take for granted, like regular rain and clean air.
In tropical nations, many developing and debt-ridden, the forest is cleared in the hope of securing an economic future. Huge industrial interests, including timber, agriculture and mining, see an “endless,” profitable supply of cheap resources just waiting to be taken. Meanwhile, family farmers and loggers feel they have no option but to deforest in order to feed their families. However, innumerable studies and recent history show that little security can be found in tropical deforestation.
Thus far, our human family has erased half of our original endowment of tropical forests. Our world is now facing the greatest extinction crisis since the fall of the dinosaurs 65 million years ago. The future of over 50 percent of Earth’s plants and animals — and hundreds of human cultures — will be determined within the next few decades. Since our lives are so dependent on the forest’s bounty, our future is at stake as well.