If you mean the top ten countries with the most rain forests then they would be the following in descending order:
1. Brazil 2. Congo (Democratic Republic) 3. Peru 4. Indonesia 5. Columbia 6. Papa New Guinea 7. Venezuela 8. Bolivia 9. Mexico 10. Suriname
As you will notice, all the countries listed above have a very similar climate in common. This is because rain forests are only found in countries in the tropics; which are very hot and humid.
These climates have nearly year-round sun and so the temperature is near constant which makes for the perfect conditions for rainforests to thrive. As the name suggests, although they are based in hot climates, rainforests do cope with a lot of downpours. In the tropics it is very common to have sharp sudden rainstorms that can bring inches of rain.
Although northern hemisphere countries have even more rain than the tropics, due to the dramatic fall and rise in temperatures, the conditions would not be conducive to rainforests and so they would flourish in the same way as they do in their more suited tropical climate. Rainforests have actually become tourist attractions in recent years. Due to the stunning scenery and the array of wildlife that reside in the forests, tourists find it fascinating and a completely different world.
This is a very BIG topic, you would have to choose what area of the world you want to talk about, but if you are going to be general the the following are some of the countries that have rain forests. One of the biggest rain forest can be found in south America, the Amazon Rain forest is part of Colombia, Ecuador, Peru, Bolivia, Brazil and Venezuela, and Guyana, Suriname, French Guiana, and a very small part of northern Argentina. Other countries like Panama, Costa Rica, and 15 nations in Africa (from Guinea and Sierra Leone in the western part of Africa to the island of Madagascar in the east of Africa), Some southeast Asian countries like India, Bangladesh, Sri Lanka, Indonesia, Malaysia, Myanmar (Burma) and Northeastern coast of Queensland in Australia, all have Tropical Rain forests. We can also find Temperate Rain Forest in Australia, New Zealand, Chile, Norway, Japan, Great Britain and the northwest coast of North America. To get more information, I would google rain forest and go from there.
Temperate rainforest regions of the world include the Pacific temperate rainforests of northwestern North America (from Alaska's Kodiak Island to northern California). These include the British Columbia mainland coastal forests (many temperate rainforests are located all over British Columbia in Canada), the Central Pacific coastal forests, the Central and Southern Cascades forests, Klamath-Siskiyou forests, Mount Rainier National Park, Mount Saint Helens National Monument, the Northern California coastal forests, the Northern Pacific coastal forests, Olympic National Park, Point Reyes National Seashore, Queen Charlotte Islands, Redwood National Park, Tongass National Forest and Vancouver Island.
Then there are Valdivian temperate rainforests and Magellanic subpolar forest ecoregions in South America (Chile and Argentina); the Knysna-Amatole coastal rainforests and the Tsitsikamma National Park in South Africa, the Fiordland and Westland temperate rainforests in New Zealand, the Tasmanian temperate rainforests, Victoria's Otway Ranges, the Strzelecki Ranges, the Dandenong Ranges, East Gippsland southeast New South Wales, Cool temperate rainforest (on the New South Wales-Queensland border), the Border Ranges National Park and the Lamington National Park in Australia; The Colchian rainforests in Georgia and Turkey; the Taiheiyo (Pacific) evergreen rainforests in Japan; Taiwan's mountain coniferous rainforests (located in Taiwan's Central Mountain Ranges) and the temperate rainforests of northwest Europe in Scotland, Ireland, Norway and Iceland. Tropical rainforests can be found in various southeast Asian, South America, African and Australasian countries.