An urn is a vase, often with a cover, with a typically narrowed neck above a rounded body and a footed pedestal. Describing a vessel as an "urn", as opposed to a vase or other terms, generally reflects its use rather than any particular shape or origin. The term is especially often used for funerary urns, vessels used in burials, either to hold the cremated ashes or as grave goods, but is used in many other contexts.

Large sculpted vases are often called urns, whether placed outdoors, in gardens or as architectural ornaments on buildings, or kept inside. In catering, large vessels for serving tea or coffee are often called "tea-urns", even when they are metal cylinders of purely functional design.

Urns are also a common reference in thought experiments in probability wherein marbles or balls of different colors are used to represent different results and the urn represents the "container" of the whole set of possible states.

Funerary urns (also called cinerary urns and burial urns) have been used by many civilizations. After death, corpses are cremated, and the ashes are collected and put in an urn. Pottery urns, dating from about 7000 BC, have been found in an early Jiahu site in China, where a total of 32 burial urns are found, and other early finds are in Laoguantai, Shaanxi. There are about 700 burial urns unearthed over the Yangshao (5000–3000 BC) areas consisting of more than 50 varieties of form and shape. The burial urns were used mainly for children, but also sporadically for adults.

The Urnfield culture (c. 1300 BC – 750 BC), a late Bronze Age culture of central Europe, takes its name from its large cemeteries of urn burials. The discovery of a Bronze Age urn burial in Norfolk, England, prompted Sir Thomas Browne to describe the antiquities found. He expanded his study to survey burial and funerary customs, ancient and current, and published it as Hydriotaphia or Urn Burial (1658).

In ancient Greece, cremation was usual, and the ashes were typically placed in a painted Greek vase. In particular, the lekythos, the shape of vase, was used for holding oil in funerary rituals. Romans placed the urns in a niche in a collective tomb called a columbarium (literally, dovecote). The interior of a dovecote usually has niches to house doves. Cremation urns were also commonly used in early Anglo Saxon England, and in many Pre-Columbian cultures.

In some later European traditions, a king's heart, and sometimes other organs, could be placed in one or more urns upon his death, as happened with King Otto of Bavaria in 1916, and buried in a different place from the body, to symbolize a particular affection for the place by the departed.

In the modern funeral industry, cremation urns of varying quality, elaborateness, and cost are offered, and urns are another source of potential profit for an industry concerned that a trend toward cremation might threaten profits from traditional burial ceremonies. Biodegradable urns are sometimes used for both human and animal burial. They are made from eco-friendly materials such as recycled or handmade paper, salt, cellulose or other natural products that are capable of decomposing back into natural elements, and sometimes include a seed intended to grow into a tree at the site of the burial.