There are two main coffee processing methods: washed coffee and natural coffee. For washed process coffee, the skin and fruit of the coffee cherry are removed and the coffee cherry is washed down to its parchment before drying. For natural process coffee, the coffee cherry is laid out to dry without removing any of the cherry's skin or fruit. For this reason, natural processed coffee is sometimes referred to as "dry processed" coffee, since it doesn't require any water. This makes natural processed coffees popular in regions with less abundant water resources like Ethiopia, where natural coffee production has been a staple of the coffee culture for hundreds of years.
Natural coffees are usually dried on raised beds, which allows air to circulate under the coffee and promotes even drying. Producers will also rake or turn the cherries throughout the day to make sure that the coffee dries evenly and to prevent clumps from forming. Depending on the season, some producers cover the cherry during the hottest or coolest parts of the day to protect the cherry - so it's a lot more complicated than just letting the coffee sit in the sun!
After the cherry is dried to the appropriate moisture content, the coffee is taken to a dry-milling facility where the dried husk and fruit of the cherry is removed, and the coffee beans are bagged and prepared for export.
Natural coffees are known to have much more funky, interesting flavors than your traditional washed coffee. This is because as the coffee cherry dries the sugars in the fruit will start to ferment, imparting all sorts of unique flavors into the coffee bean that you'll taste as you brew. Farmers take great care to control how quickly the coffee cherries dry by building adjustable shade structures and turning the cherries regularly as they dry. This helps ensure that the coffee doesn't ferment too much or too little, which can affect the taste and quality of the end product.