A coffee bean (Arabic بُن bunn) is a misnomer for a seed of a coffee plant. It is the pit inside the red or purple fruit often referred to as a cherry. Even though they are seeds, they are incorrectly referred to as 'beans' because of their resemblance to true beans. The fruits - coffee cherries or coffee berries - most commonly contain two stones with their flat sides together. A small percentage of cherries contain a single seed, instead of the usual two. This is called a peaberry. Like Brazil nuts (a seed) and white rice, coffee seeds consist mostly of endosperm.

The two most economically important varieties of coffee plant are the Arabica and the Robusta; 75-80% of the coffee produced worldwide is Arabica and 20% is Robusta. Arabica seeds consist of 0.8-1.4% caffeine and Robusta seeds consist of 1.7-4% caffeine. As coffee is one of the world's most widely consumed beverages, coffee seeds are a major cash crop, and an important export product, counting for over 50% of some developing nations' foreign exchange earnings. The United States imports more coffee than any other nation. In 2009 the average person in the United States consumed 4.09 kg (9 lbs) of coffee.