The two major types of coffee are Arabica and Robusta. The hardier and less desirable robustas are grown at lower altitudes and in hotter climates. Generally and with a few exceptions, robusta coffees tend to make up a high percentage of commercial and instant coffee blends. Arabica coffees on the other hand, are less hardy but possess more desirable characteristics. Arabicas are grown at higher altitudes (4-6,000 ft. above sea level). The average arabica tree produces a meager 1-2 lbs. of coffee per year. Of all the arabica coffees produced, less than 8% meet the quality requirements for "specialty coffee".  Coffee is generally processed by a variation of 2 methods: wet/washed and dry/natural. Most specialty coffees are processed by the "wet" or washed method. After being picked at the peak of ripeness, the coffee beans are "squeezed" out of the cherry-like skin by a pulper and separated with the aid of water. The beans are then allowed to ferment for 36 to 72 hours and washed with clean water. This process removes the mucilage or fruity layer before the coffee beans are put out to dry for about 2-3 weeks. The beans are turned several times a day to ensure that all the beans dry evenly. After an additional "conditioning" period of about 6-8 weeks, the coffees are then milled (to remove the parchment or  pergamino layer) before being sorted to remove imperfections and graded for size, weight, and most importantly - liquor or cup quality. In the dry or natural method, after being picked, the whole cherries are placed directly on drying patios and left to dry in the sun. The dried cherries are later milled, sorted and graded for export. 

Traditionally, there are several intermediaries. Depending on the country of origin, the export process will be a variation of: 

a) direct export by an estate to an importing broker or roaster 

 b) the mill or co-operative sells or auctions coffees to exporters who in turn sell to importing brokers or roasters.

Once a broker has bought a particular lot of coffee, sales samples will be sent out to roasters to evaluate.  As with most agricultural products, not all lots are the same. And so, it is up to the roastmaster to buy, blend and roast each coffee in such a manner that you, the consumer, can expect the same product each time you buy a pound of your favorite coffee from your retailer.