Artillery
Artillery piece: Although not called by that name, siege engines performing the role recognizable as artillery have been employed in warfare since antiquity. The first known catapult was developed in Syracuse in 399 BC. Until the introduction of gunpowder into western warfare, artillery was dependent upon mechanical energy which not only severely limited the kinetic energy of the projectiles, it also required the construction of very large engines to accumulate sufficient energy. A 1st-century BC Roman catapult launching 6.55 kg (14.4 lb) stones achieved a kinetic energy of 16 kilojoules, compared to a mid-19th-century 12-pounder gun, which fired a 4.1 kg (9.0 lb) round, with a kinetic energy of 240 kilojoules, or a 20th-century US battleship that fired a 1,225 kg (2,701 lb) projectile from its main battery with an energy level surpassing 350 megajoules.
From the Middle Ages through most of the modern era, artillery pieces on land were moved by horse-drawn gun carriages. In the contemporary era, artillery pieces and their crew relied on wheeled or tracked vehicles as transportation. These land versions of artillery were dwarfed by railway guns; the largest of these large-calibre guns ever conceived – Project Babylon of the Supergun affair – was theoretically capable of putting a satellite into orbit. Artillery used by naval forces has also changed significantly, with missiles generally replacing guns in surface warfare.
Over the course of military history, projectiles were manufactured from a wide variety of materials, into a wide variety of shapes, using many different methods in which to target structural/defensive works and inflict enemy casualties. The engineering applications for ordnance delivery have likewise changed significantly over time, encompassing some of the most complex and advanced technologies in use today.
In some armies, the weapon of artillery is the projectile, not the equipment that fires it. The process of delivering fire onto the target is called gunnery. The actions involved in operating an artillery piece are collectively called "serving the gun" by the "detachment" or gun crew, constituting either direct or indirect artillery fire. The manner in which gunnery crews (or formations) are employed is called artillery support. At different periods in history, this may refer to weapons designed to be fired from ground-, sea-, and even air-based weapons platforms.

Crew: Some armed forces use the term "gunners" for the soldiers and sailors with the primary function of using artillery.

The gunners and their guns are usually grouped in teams called either "crews" or "detachments". Several such crews and teams with other functions are combined into a unit of artillery, usually called a battery, although sometimes called a company. In gun detachments, each role is numbered, starting with "1" the Detachment Commander, and the highest number being the Coverer, the second-in-command. "Gunner" is also the lowest rank, and junior non-commissioned officers are "Bombardiers" in some artillery arms.
Batteries are roughly equivalent to a company in the infantry, and are combined into larger military organizations for administrative and operational purposes, either battalions or regiments, depending on the army. These may be grouped into brigades; the Russian army also groups some brigades into artillery divisions, and the People's Liberation Army has artillery corps.
The term "artillery" also designates a combat arm of most military services when used organizationally to describe units and formations of the national armed forces that operate the weapons.

Tactics: During military operations, field artillery has the role of providing support to other arms in combat or of attacking targets, particularly in-depth. Broadly, these effects fall into two categories, aiming either to suppress or neutralize the enemy, or to cause casualties, damage, and destruction. This is mostly achieved by delivering high-explosive munitions to suppress, or inflict casualties on the enemy from casing fragments and other debris and from blast, or by destroying enemy positions, equipment, and vehicles. Non-lethal munitions, notably smoke, can also suppress or neutralize the enemy by obscuring their view.
Fire may be directed by an artillery observer or another observer, including crewed and uncrewed aircraft, or called onto map coordinates.
Military doctrine has had a significant influence on the core engineering design considerations of artillery ordnance through its history, in seeking to achieve a balance between the delivered volume of fire with ordnance mobility. However, during the modern period, the consideration of protecting the gunners also arose due to the late-19th-century introduction of the new generation of infantry weapons using conoidal bullet, better known as the Minié ball, with a range almost as long as that of field artillery.
The gunners' increasing proximity to and participation in direct combat against other combat arms and attacks by aircraft made the introduction of a gun shield necessary. The problems of how to employ a fixed or horse-towed gun in mobile warfare necessitated the development of new methods of transporting the artillery into combat. Two distinct forms of artillery were developed: the towed gun, used primarily to attack or defend a fixed-line; and the self-propelled gun, intended to accompany a mobile force and to provide continuous fire support and/or suppression. These influences have guided the development of artillery ordnance, systems, organizations, and operations until the present, with artillery systems capable of providing support at ranges from as little as 100 m to the intercontinental ranges of ballistic missiles. The only combat in which artillery is unable to take part is close-quarters combat, with the possible exception of artillery reconnaissance teams.

Etymology: The word as used in the current context originated in the Middle Ages. One suggestion is that it comes from French atelier, meaning the place where manual work is done.
Another suggestion is that it originates from the 13th century and the Old French artillier, designating craftsmen and manufacturers of all materials and warfare equipments (spears, swords, armor, war machines); and, for the next 250 years, the sense of the word "artillery" covered all forms of military weapons. Hence, the naming of the Honourable Artillery Company, which was essentially an infantry unit until the 19th century.
Another suggestion is that it comes from the Italian arte de tirare (art of shooting), coined by one of the first theorists on the use of artillery, Niccolò Tartaglia.

History: Mechanical systems used for throwing ammunition in ancient warfare, also known as "engines of war", like the catapult, onager, trebuchet, and ballista, are also referred to by military historians as artillery.

Medieval: During medieval times, more types of artillery were developed, most notably the counterweight trebuchet. Traction trebuchets, using manpower to launch projectiles, have been used in ancient China since the 4th century as anti-personnel  weapons. The much more powerful counterweight trebuchet was invented in the eastern Mediterranean region in the 12th century, with the earliest definite attestation in 1187.

Invention of gunpowder: Early Chinese artillery had vase-like shapes. This includes the "long range awe inspiring" cannon dated from 1350 and found in the 14th century Ming dynasty treatise Huolongjing. With the development of better metallurgy techniques, later cannons abandoned the vase shape of early Chinese artillery. This change can be seen in the bronze "thousand ball thunder cannon", an early example of field artillery. These small, crude weapons diffused into the Middle East (the madfaa) and reached Europe in the 13th century, in a very limited manner.
In Asia, Mongols adopted the Chinese artillery and used it effectively in the great conquest. By the late 14th century, Chinese rebels used organized artillery and cavalry to push Mongols out.
As small smooth-bore barrels, these were initially cast in iron or bronze around a core, with the first drilled bore ordnance recorded in operation near Seville in 1247. They fired lead, iron, or stone balls, sometimes large arrows and on occasions simply handfuls of whatever scrap came to hand. During the Hundred Years' War, these weapons became more common, initially as the bombard and later the cannon. Cannon were always muzzle-loaders. While there were many early attempts at breech-loading designs, a lack of engineering knowledge rendered these even more dangerous to use than muzzle-loaders.

Expansion of use: In 1415, the Portuguese invaded the Mediterranean port town of Ceuta. While it is difficult to confirm the use of firearms in the siege of the city, it is known the Portuguese defended it thereafter with firearms, namely bombardas, colebratas, and falconetes. In 1419, Sultan Abu Sa'id led an army to reconquer the fallen city, and Marinids brought cannons and used them in the assault on Ceuta. Finally, hand-held firearms and riflemen appear in Morocco, in 1437, in an expedition against the people of Tangiers. It is clear these weapons had developed into several different forms, from small guns to large artillery pieces.
The artillery revolution in Europe caught on during the Hundred Years' War and changed the way that battles were fought. In the preceding decades, the English had even used a gunpowder-like weapon in military campaigns against the Scottish. However, at this time, the cannons used in battle were very small and not particularly powerful.