Coffee is a beverage brewed from roasted, ground coffee beans. Darkly colored, bitter, and slightly acidic, coffee has a stimulating effect on humans, primarily due to its caffeine content, but decaffeinated coffee is also commercially available. There are also various coffee substitutes.

Coffee production begins when the seeds from coffee cherries (the Coffea plant's fruits) are separated to produce unroasted green coffee beans. The "beans" are roasted and then ground into fine particles. Coffee is brewed from the ground roasted beans, which are typically steeped in hot water before being filtered out. It is usually served hot, although chilled or iced coffee is common. Coffee can be prepared and presented in a variety of ways (e.g., espresso, French press, caffè latte, or already-brewed canned coffee). Sugar, sugar substitutes, milk, and cream are often added to mask the bitter taste or enhance the flavor.

Though coffee is now a global commodity, it has a long history tied closely to food traditions around the Red Sea. The earliest credible reports of coffee drinking pertain to the plant's use among the Sufis of Yemen (southern Arabia) in the middle of the 15th century. Up to the end of the 17th century, most of the world’s coffee was imported from Yemen. But as the beverage gained in popularity, coffee also started to be cultivated in Java in the 17th century, as well as in the Americas from the 18th century onward.

The two most commonly grown coffee bean types are C. arabica and C. robusta. Coffee plants are cultivated in over 70 countries, primarily in the equatorial regions of the Americas, Southeast Asia, the Indian subcontinent, and Africa. Green, unroasted coffee is traded as an agricultural commodity. The global coffee industry is worth $495.50 billion, as of 2023. In 2023, Brazil was the leading grower of coffee beans, producing 31% of the world's total, followed by Vietnam. While coffee sales reach billions of dollars annually worldwide, coffee farmers disproportionately live in poverty. Critics of the coffee industry have also pointed to its negative impact on the environment and the clearing of land for coffee-growing and water use.

The word coffee entered the English language in 1582 via the Dutch koffie, borrowed from the Ottoman Turkish kahve (قهوه), borrowed in turn from the Arabic qahwah (قَهْوَة). Medieval Arabic lexicons traditionally held that the etymology of qahwah meant 'wine', given its distinctly dark color, and was derived from the verb qahiya (قَهِيَ), 'to have no appetite'. The word qahwah most likely meant 'the dark one', referring to the brew or the bean; qahwah is not the name of the bean, which are known in Arabic as bunn and in Cushitic languages as būn. Semitic languages have the root qhh, 'dark color', which became a natural designation for the beverage. Its cognates include the Hebrew qehe(h) 'dulling' and the Aramaic qahey ('give acrid taste to'). Although etymologists have connected it with a word meaning 'wine', it is also thought to be from the Kaffa region of Ethiopia.

The terms coffee pot and coffee break originated in 1705 and 1952, respectively.

The earliest recorded reference to the coffee bean and its qualities appears in a treatise by Al-Razi, which describes the bean, referred to as "bunchum", as "hot and dry and very good for the stomach". According to later accounts, bunchum was made from a root rather than from coffee beans.

There is no confirmed evidence, either historical or archaeological, of coffee as a drink being consumed before the 15th century. The beverage appears to be a relatively recent development. By the late 15th century, however, coffee drinking was well established among Sufi communities in Yemen.