A cannon is any tubular piece of artillery that uses gunpowder or other usually explosive-based propellants to launch a projectile over a distance. Cannon vary in caliber, range, mobility, rate of fire, angle of fire, and firepower; different forms of cannon combine and balance these attributes in varying degrees, depending on their intended use on the battlefield. The word cannon is derived from several languages, in which the original definition can usually be translated as tube, cane, or reed. In modern times, cannon has fallen out of common usage, usually replaced by "guns" or "artillery", if not a more specific term, such as "mortar" or "howitzer".

First used in China, cannon were among the earliest forms of gunpowder artillery, and over time replaced siege engines—among other forms of aging weaponry—on the battlefield. The first hand cannon appeared during the 1260 Battle of Ain Jalut between the Mamluks and Mongols in the Middle East. The first cannon in Europe were probably used in Iberia, during the Reconquista, in the 13th century, and English cannon were first deployed in the Hundred Years' War, at the Battle of Crécy, in 1346. It was during this period, the Middle Ages, that cannon became standardized, and more effective in both the anti-infantry and siege roles. After the Middle Ages most large cannon were abandoned in favor of greater numbers of lighter, more maneuverable pieces. In addition, new technologies and tactics were developed, making most defenses obsolete; this led to the construction of star forts, specifically designed to withstand artillery bombardment and the associated siege tactics.

Cannon also transformed naval warfare: the Royal Navy, in particular, took advantage of their firepower. As rifling became more commonplace, the accuracy of cannon was significantly improved, and they became deadlier than ever, especially to infantry. In World War I, the majority of all deaths were caused by cannon; they were also used widely in World War II. Most modern cannon are similar to those used in the Second World War, except for heavy naval guns, which have been replaced by missiles. In particular, autocannon have remained nearly identical to their World War II counterparts.

Etymology and terminology

Cannon is derived from the Old Italian word cannone, meaning large tube, which came from Latin canna, in turn originating from the kanna—Greek for cane, or reed—and ultimately deriving from the Akkadian term qanu, meaning tube or reed. The word has been used to refer to a gun since 1326 in Italy, and 1418 in England. Cannon serves both as the singular and plural of the noun, although the plural cannons is also correct.