In the coffee world, there are four (4) primary ways to process coffee. This is my attempt to give a super basic summary of each process, including what it means for the farmers, and for you and me when we enjoy the coffee in our homes, cafes, and offices. Each process begins when the farmers pick the ripe fruit from the coffee tree, often times called coffee cherries. Most of the time, ripe coffee cherries are red, but sometimes are orange or yellow in certain coffee varieties. If the coffee cherry is not ripe when picked, the overall taste of the coffee will negatively affected. After picking ripe cherries, the farmers then decide how they want to process them.
Pulp - The outer skin of the coffee fruit is removed with the help of a machine (pulper)
Hull/Parchment - The inner skin (or parchment) of the coffee fruit is removed with the help of a machine (huller)
Mucilage - The sticky remainder on the coffee bean from the fruit after the coffee cherry is pulped.
The following image will be helpful in understanding the coffee fruit or cherry. Also, Sweet Maria's has some great pictures of coffee beans on this page on their website.