Coffee beans are the seeds of the coffee cherry tree, and each coffee cherry produces 2 green beans. Although there are many species of coffee trees, only one produces exceptional coffee.
Coffee Arabica which was first found growing in Yemen centuries ago and is the sole species of quality beans. The most widely cultivated coffee plant Arabica thrives at higher altitudes, where the beans mature slowly and have time to develop body and density. At these higher altitudes they may take six or seven months, but at this slower rate of fruit maturation gives the beans more time to develop flavor. Slower maturing, high density Arabica beans are referred to as hard beans.
Coffee Robusta is the type you are most likely to drink when you follow instructions to add water and stir. Discovered in Africa toward the end of the nineteenth century Robusta is relatively new to the coffee industry but its role is significant. Because of its hardiness, low yield and ability to grow at low altitudes, its beans are cheaper to produce. This makes them ideal for blending with Arabica and for use in instant coffee. For those who like caffeine, Robusta have twice as much kick as Arabica. Although because of this, their flavor tends to be harsh and pungent.