The genus Coffea, which belongs to the red pepper family, comprises over 100 species; only two of them are important for commercial cultivation: Arabica (C. arabica) and Robusta coffee (C. caneophora). These evergreen trees grow up to five and eight meters tall, respectively. Their small white flowers produce coffee cherries, each of whose pulp encloses two seeds: the coffee beans. Because new blossoms are formed over a long period of time, the trees bear blossoms and fruits in all degrees of ripeness at the same time.

Arabica coffee has its home in the Ethiopian highlands, while Robusta was originally at home in West and Central Africa and copes better with the climatic conditions in the lowlands. Today, coffee plantations are established throughout the world in the tropics and subtropics, the prerequisite being loose soil that is well supplied with nutrients. Harvesting the red coffee cherries takes more than three months. They are dried in the sun until the seeds "rattle" inside them. Then the coffee beans are freed from their hulls and enter the market as green coffee.

In addition to the typical aroma of roasted seeds, caffeine is the substance that coffee is all about. Surprisingly, coffee initially has a calming effect: if you lie down after a cup of coffee, you fall asleep well; that's why many hospitals like to serve coffee before you go to bed. Those who stay awake experience the invigorating and stimulating effect of caffeine - sleep is then out of the question. Since caffeine is also absorbed through the mucous membranes of the mouth, its effect is more rapid if the sip of coffee (or a product containing caffeine) is held in the mouth for longer.