The book, "Ecotourism: An Introduction" by David A. Fennell, attributes the concept of ecotourism to Hetzer, who in 1965 proposed four points for responsible tourism: to have minimum impact on the environment; minimum impact on the culture of the host country; maximum benefit to the host country's economy; and maximum recreational enjoyment by the visitor.
Ecotourism benefits both the traveler and the country to which she is traveling. Ecotourists learn about the culture of the host country instead of confining their travel to tourist hot spots, and since ecotourism is responsible tourism, it preserves the environment while providing financial gain for locals.
Ecotourism means using local services--dine in locally owned restaurants, stay in local hotels and shop at local stores and markets, rather than internationally owned businesses. It also means being respectful of the customs of the locale, paying fair prices and taking care of the environment as you travel.
Many people believe that ecotourism is expensive, or that it involves backpacking through exotic locations such as the rainforest. While this can be true, it doesn't have to be; the International Ecotourism Society points out that you can practice responsible travel in any location, and within a wide range of prices and comfort levels.
Before planning any sustainable vacation, check the U.S. Department of State's international travel warnings and alerts. This will help you to avoid any safety problems while traveling.