Espresso coffee contains less caffeine than regular coffee.

A cup of regular brewed coffee contains 115 mg of caffeine, espresso (and coffee brewed in a percolator) contains about 80 mg, and instant coffee contains only 65 mg. Decaffeinated coffee is not complete without caffeine, it is about 3 milligrams. A can of Coca-Cola contains about 45 mg of caffeine, Pepsi 38 mg, Mountain Dew 54 mg, and TAB47 mg. Tea contains about 40 milligrams of caffeine, while an ounce of chocolate contains about 20 milligrams.

Coffee is the world's most popular stimulant: four out of five Americans drink it and consume more than 400 million cups a day. Scandinavian countries consume more than 12 kilograms per capita. The coffee industry employs more than 2.5 million people, making it second only to oil in world transactions.

Although coffee trees are thought to have grown near the Red Sea since the 7th century, the 15th-century Arab writer Shehadingben writes that Ethiopians enjoyed coffee as early as anyone can recall. By the 16th century, coffee trees were found all over the Arabian Yemen. After the Turkish ambassador introduced it to the court of Louis XIV in 1669, Europeans soon got a taste of it. Several years later, the Netherlands introduced coffee to Java. In 1714, the Frenchman Deske stayed and planted a coffee tree on the island of Martinique. Coffee cultivation soon spread from Guiana in France to Brazil and Central America. Today, coffee is grown in most parts of the world.

Coffee is the seed in the berries of a coffee tree, which produces about 1 kilogram (2 pounds) of coffee a year. There are more than 25 types of coffee, of which the three main commercial types are Robaster, Libby and Arabica, which account for 70% of the total output.

Caffeine increases the power of aspirin and other painkillers, which is why it exists in some drugs. Ironically, the decline of caffeine is also one of the most common causes of headaches. Women who drink two or more cups of coffee a day increase their risk of osteoporosis. However, it can be offset by drinking milk or yogurt to replace the lost calcium. Many studies have found that caffeine absorption impairs fertility and drinking during pregnancy can lead to preterm delivery or infant defects.

Caffeine can be removed from coffee by using chlorinated hydrocarbon solvents to treat green coffee beans. Instant coffee is made by mixing ground and roasted coffee with hot water, followed by drying equipment and high pressure dehydration, leaving only coffee powder. Some coffee products use chicory (a wildflower herb), figs, dates, malt or barley as coffee substitutes, which is a far cry from real coffee.