ALL COFFEE HAS TO BE PROCESSED
The coffee bean is actually a seed of the coffee cherry. Cherries are picked at the peak of ripeness (or should be) and the skin, flesh, and sticky mucilage must be removed to get the coffee from the farm to the roaster. The difference in processing has to do with when and how these are removed, and has significant flavor implications. Also washed coffees are not "unnatural." All coffee needs human intervention to produce that nectar of the gods we know and love.
This is the most common process, and sometimes referred to as "wet process." The coffee cherries are picked and taken to a wet mill, washing station, or factory (all industry terms for the same thing). Here, different methods involving water are used to remove the skin, fruit and mucilage from the coffee seed. Err, bean.
Beans are then dried on patios or raised beds with frequent rotation until the desired moisture content is reached.
Compared to natural coffees, washed coffees have higher acidity, a cleaner mouthfeel and traditional "coffee" taste.
This is the oldest coffee process, where cherries are picked and immediately laid out to dry on patios or raised beds with the fruit still in tact. Cherries are rotated and dry in the sun for about 2 weeks or longer. During this time, the seed (bean), receives flavor from the cherry and a small amount of fermentation.
After the coffee cherry is fully dried, the skin and fruit are removed with machinery.
Compared to washed coffees, natural coffees have a heavier body and fruitier taste (or sometimes downright funky!).
There you have it!