There are many, many, many types. In order to give a good overview, some background knowledge is useful. What all types of coffee have in common is that all are produced from the pits of coffee cherries, the fruits borne by trees in the genus coffea (coffee beans are technically seeds of these trees, not beans). Coffee cherries are harvested from coffee trees, the pits are removed and processed, producing green coffee beans. These are then roasted, ground, and brewed.
Coffee can vary on any of the following factors:
- Bean Variety – There are two major bean varieties of coffee: arabica and robusta. Arabica coffees are more ubiquitous and generally regarded as superior in quality to robusta coffees. If you are buying coffee from a coffee shop, ordering it at a restaurant, or brewing it at home, there is a very good chance you are drinking an arabica variety. Robusta is easier to grow and a less temperamental crop than arabica, contains quite a bit more caffeine, and generally is poorer quality than arabica. Robusta varieties are often used in instant coffee.
- Processing Method – There are two major processing types for green coffee beans: washed and unwashed. Washed coffees remove the cherry before the bean is left to dry, while unwashed coffees have their beans removed from the cherries after drying. Unwashed coffees often come from Africa and Indonesia and have richer, earthier flavors, while washed coffees often come from Latin America, and are smoother and fruitier.
- Geographic Origin – One of the most important factors, as coffee flavors vary greatly with geography, climate, and soil composition. For example, Ethopian coffees tend to be rich, full-bodied, and wine-like, Hawaiian coffees like Kona tend to be more acidic (flavor term, not pH), and Latin American coffees tend to be more medium bodied, fruity, and floral.
- Roast – Roasting is a complex process that can produce varying degrees of flavor and caffeine content. Roasts levels can include light/half-city, medium/full-city, full (Viennese/Italian), and double (French), in order of increasing boldness. Contrary to popular opinion, lighter roasts tend to have more caffeine than darker roasts.
- Brewing method – Can include drip filter, french press, percolated, espresso, or other methods. Brewing method also makes a big difference, with coffee aficionados generally preferring french press and espresso.
The most expensive type of coffee is Kopi Luwak from Sumatra, Bali, Java, and Sulawesi. Kopi Luwak roughly translates to “civet coffee” in English, and is called such because the beans are harvested from the droppings of civets (a cat-like mammal from Indonesia). The beans are supposedly of superior quality because the civets choose only the ripest coffee beans to eat from coffee trees, and are processed in a unique way by the civets digestive tract.