Trimethylxanthine, sometimes referred to by its less accurate and far more boring name as “caffeine”, is a bitter, white crystalline xanthine alkaloid and a stimulant drug. Caffeine is found in varying quantities in the seeds, leaves, and fruit of some plants. One of the world’s primary sources of caffeine is the coffee “bean” (which is the seed of the coffee plant), from which coffee is brewed.

Caffeine content in coffee varies widely depending on the type of coffee bean and the method of preparation used; even beans within a given bush can show variations in concentration. In general, dark-roast coffee has very slightly less caffeine than lighter roasts because the roasting process reduces a small amount of the bean’s caffeine content.

In humans, caffeine acts as a central nervous system stimulant, temporarily warding off drowsiness and restoring alertness. Beverages containing caffeine, such as coffee, tea, and soft drinks, enjoy great popularity. In North America, 90% of adults consume caffeine daily. Global consumption of caffeine has been estimated at 120,000 tonnes per year, making it the world’s most popular psychoactive substance. This amounts to one serving of a caffeinated beverage for every person every day.