A Central nervous system stimulant of the methylxanthine class, caffeine is the most widely consumed psychoactive drug in the world. The primary mechanism of action that explains caffeine’s primary effects is that it reversibly blocks the effects of adenosine on receptors, preventing the onset of drowsiness sensations. Caffeine is also known to stimulate certain areas of the autonomic nervous system as well. It is a bitter, white crystalline purine, a methylxanthine alkaloid, and is related chemically to both adenine and guanine bases of DNA and RNA. Naturally occurring caffeine is found in the seeds, nuts, and leaves of plants found in South American and East Asia, conferring on those plants a number of reproductive and survival benefits. Caffeine is extracted by steeping the caffeine containing plant products in water, a process known as infusion. It offers both health benefits in terms of regulating the health of the central and autonomic nervous systems, though it has been shown to reduce the risk of coronary artery disease and stroke if consumed in quantity on a daily basis.