There are over 125 species of coffee in the world today but only two are viable commercially, coffea arabica and coffea canephora, more commonly known as robusta. These are grown in over 70 countries, primarily between the tropics of Cancer and Capricorn. This is often referred to as the coffee belt. In speciality coffee we focus on arabica. Arabica has half the caffeine compared to robusta and is more complex, flavourful and less bitter. Caffeine acts like a natural pesticide, which is why arabica is grown at high elevation and robusta at lower.
Within the arabica species there are many varieties known as cultavars (cultivated varieties). These are similar to the varieties you find with grapes and other fruits. Some examples of arabica cultavars are Typica, Bourbon, Castillo, Caturra, Pacamara and SL-28.