Coffee is darkly colored, bitter, slightly acidic and has a stimulating effect in humans, primarily due to its caffeinecontent. It is one of the most popular drinks in the world, and it can be prepared and presented in a variety of ways (e.g., espresso, French press, café latte). It is usually served hot, although iced coffee is a popular alternative. Clinical studies indicate that moderate coffee consumption is benign or mildly beneficial in healthy adults, with continuing research on whether long-term consumption lowers the risk of some diseases, although those long-term studies are of generally poor quality.
The earliest credible evidence of coffee-drinking appears in modern-day Yemen in southern Arabia in the middle of the 15th century in Sufi shrines. It was here in Arabia that coffee seeds were first roasted and brewed in a similar way to how it is now prepared. But the coffee seeds had to be first exported from East Africa to Yemen, as the Coffea arabicaplant is thought to have been indigenous to the former. Yemeni traders took coffee back to their homeland and began to cultivate the seed. By the 16th century, the drink had reached Persia, Turkey, and North Africa. From there, it spread to Europe and the rest of the world.