Cranberries are a group of evergreen dwarf shrubs or trailing vines in the subgenus Oxycoccus of the genus Vaccinium. Cranberries are low, creeping shrubs or vines up to 2 meters (7 ft) long and 5 to 20 centimeters (2 to 8 in) in height; they have slender stems that are not thickly woody and have small evergreen leaves. The flowers are dark pink. The fruit is a berry that is larger than the leaves of the plant; it is initially light green, turning red when ripe. It is edible, but has an acidic taste.

In Britain, cranberry may refer to the native species Vaccinium oxycoccos, while in North America, cranberry may refer to Vaccinium macrocarpon. Vaccinium oxycoccos is cultivated in central and northern Europe, while V. macrocarpon is cultivated throughout the northern United States, Canada and Chile. In some methods of classification, Oxycoccus is regarded as a genus in its own right. Cranberries can be found in acidic bogs throughout the cooler regions of the Northern Hemisphere.

In 2020, the U.S., Canada, and Chile accounted for 97% of the world production of cranberries. Most cranberries are processed into products such as juice, sauce, jam, and sweetened dried cranberries, with the remainder sold fresh to consumers. Cranberry sauce is a traditional accompaniment to turkey at Christmas and Thanksgiving dinners in the U.S. and Canada, and at Christmas dinner in the United Kingdom.

Cranberries are low, creeping shrubs or vines up to 2 meters (7 ft) long and 5 to 20 centimeters (2 to 8 in) in height; they have slender, wiry stems that are not thickly woody and have small evergreen leaves. The flowers are dark pink, with very distinct reflexed petals, leaving the style and stamens fully exposed and pointing forward. They are pollinated by bees. The fruit is a berry that is larger than the leaves of the plant; it is initially light green, turning red when ripe. It has an acidic taste which usually overwhelms its sweetness.

There are 4–5 species of cranberry, classified by subgenus:

Cranberries are related to bilberries, blueberries, and huckleberries, all in Vaccinium subgenus Vaccinium. These differ in having bell-shaped flowers, petals that are not reflexed, and woodier stems, forming taller shrubs.

The name cranberry derives from the Middle Low German kraanbere (English translation, craneberry), first named as cranberry in English by the missionary John Eliot in 1647. Around 1694, German and Dutch colonists in New England used the word, cranberry, to represent the expanding flower, stem, calyx, and petals resembling the neck, head, and bill of a crane. The traditional English name for the plant more common in Europe, Vaccinium oxycoccos, fenberry, originated from plants with small red berries found growing in fen (marsh) lands of England.

American Revolutionary War veteran Henry Hall first cultivated cranberries in the Cape Cod town of Dennis around 1816. In the 1820s, Hall was shipping cranberries to New York City and Boston from which shipments were also sent to Europe. In 1843, Eli Howes planted his own crop of cranberries on Cape Cod, using the "Howes" variety. In 1847, Cyrus Cahoon planted a crop of "Early Black" variety near Pleasant Lake, Harwich, Massachusetts.