Artillery
"I took ballistics in school. Fascinating subject! Things go up, things go down!"
- – Company of Heroes
"Artillery is the god of modern war."
- – Joseph Stalin
"In peace the cry is for mobility, in war for weight of shell."
- – Alan Brooke
If you were to ask any neckbeard into military history what they liked most about it, you'd get a few different answers. Some would tell you it's all about stories of regular humans going beyond their limits to beat back impossible odds, others are more interested in the organization and logistics needed to feed and move thousands of people.
But for the elegan/tg/entlemen among us, it's all about the big guns that go boom. Even before the advent of gunpowder and cannons, humanity has long looked for ways to fling shit at their enemies from a safe distance, preferably outside of their opponent's range, and ideally, beyond their line-of-sight.
Nowadays, Artillery refers to Cannons and Cannon-accessories, like Rockets and Missiles, but we apply the label to any weapon that launches munitions far beyond the range of man-portable weapons (that being said, Mortars are still man-portable, so don't take anything an anon says to be definitive)
Siege Engines
Siege Engines are mechanical devices used to damage walls or kill the defenders. Weapons like the Onager, Ballista, and the Trebuchet (which could launch a 90kg projectile over 300m) are considered the first forms of Artillery.
Unlike what vidya and certain tabletop wargames will tell you, most of these weapons were too unwieldy and generally inaccurate to use against mobile targets. They were also too complicated and fragile to transport over long distances and had to be built at the site of conflict, which is why Siege Engineers were their own specialization.
List of Siege Artillery
Bolt Weapons
These are Siege weapons that look like oversized crossbows, and are generally accurate enough with their bolts to snipe defenders on the walls, and were torsion (crank) powered. They range from the simple Roman Scorpio, to the rapid-firing Greek Polybolos, both of which were developed from the much larger Ballista, which was initially used to throw small round projectiles, but would eventually fire more accurate bolts.
Technically, though they look like Crossbows, all of these machines are more complicated than that, using a combination of springs and torsion to build up energy. Some Catapult designs actually make use of the "bow" design for added strength.
Catapults
Arguably, the most famous of those siege engines was the almighty catapult! The romans used it, the greeks used it, and oh-so-many lords and knights used it during the Middle-Ages. It wasn't the most precise weapon on the planet, but we'd lie to you if we didn't say that it as beautiful to see a flock of rocks raining on a heavily guarded castle like it's judgement day. Catapults were generally some of the simplest siege engines around, and as mentioned above, used torsion mechanisms for power.
What made them supplant the Ballista was that you could use to basically throw anything more-or-less heavy with it; Boulders, would-be cannon balls, humans, barrels, literal sacks of shit (Yes, this did happen) over a longer, arcing trajectory and with more power. And it was one easier to build. Of course, it wasn't the most effective thing on the planet at destroying things, but the point of sieges was to capture a castle, not raze one. Why pass on the opportunity of getting a free castle? The best way to penetrate it was to simply injure the people inside.
Trebuchet
But when the need to eradicate the infidels, burn their houses, slaughter their families, destroy their unholy temples and autels of doom came around, Europeans perfected of destroying shit really hard by inventing the next big thing in siege engineering; the motherfucking trebuchet. Ten to Eighteen tons of a massive wooden tower made out of "Fucketh thee, I farteth ast thoust general direction".
The Chinese technically invented it, but it consisted of using slaves very brave and loyal soldiers to pull the projectile down and then releasing it. And then, reusing the design, engineers added a counterweight that would drop down with the force of a thousand suns to flung the heaviest of projectiles directly at the enemy at incredible speeds. A technological miracle of the XIIth Century to be sure, using the wonders of levers, momentum, and gravity to do most of the work.
Started a trend among technicians and engineers to come up with new tools of warfare, most notably Da Vinci who made a whole bunch of sketches of a multitude of possible war engines that were all kinds of wonky.
Cannons and Early Gunpowder weapons
As mentioned, the Chinese had various experimentations with Gunpowder. They had weapons like exploding lances and basic rockets, the best example of which was the Korean MLRS called the Hwacha, which fired a storm of rocket-powered arrows. The Chinese also had cannons, but it wasn't until Gunpowder reached the Middle East/Europe that the tech really started to find its niche.
In the Middle East, the Gunpowder Empires (Ottomans, Safavids, and the Mughals) were credited with perfecting Cannons, but thats kinda bullshit. While the three empires were early adopters of Gunpowder into their armies and even used them to devastating effect against their gun-less neighbors (Romeaboos will forever cope and seethe about how Constantinople was taken down by a big ass gun), but they generally still relied on traditional weapons and tactics in battle. For example, going back to the Fall of Constantinople, there is a story that even though the Ottoman cannons were very good at damaging the city's famous double-walls, they weren't great at breaching at it; the rubble caused by the collapsing walls was still in the way, so the besiegers had to keep shooting at the breach until the rubble was removed.
Generally, Islamic artillery came in two flavors: large and unwieldy bombard types specifically meant for sieges and wall-breaking, and much lighter, man-sized (but still to heavy to carry) cannons firing from emplacements. Field guns were not as widespread in Europe, because the terrain and the style of warfare just didn't make them worth it.
In contrast, European artillery started out similarly, with cannons being mostly built for sieges, but this soon became an arms race of experimenting with more mobile variants. Swedish King Gustavus Adolphus is famous for making Sweden a Great Power simply by adopting smaller Field Guns that could be quickly repositioned by horse; Napoleon did the same much later, advocating for entire companies of mobile, wheeled cannons because multiple cannons enfilading the enemy army was much more useful than a single gun that couldn't even be aimed properly.
While this was happening, back in Asia, breachloaded swivel guns were the norm. These were much smaller cannons that could swivel in place and incorporated elements from Chinese, Muslim, and Indian weapons. They were breachloaded and used pre-packaged powder and ammunition, and so they could fire off multiple shots in quick succession. These were very popular in Southeast Asia, and the Mongol's fought against these weapons in their failed invasion of Java.
Artillery also included Rockets, such as the Indian Mysorean Rocket, which became the British Congreve Rocket (the Rocket's Red Glare in Traditional Americanese Music). These Rockets were as you'd expect, inaccurate and chaotic, but also spread terror and could be fitted with a variety of armaments. An attacking force would launch a bareage of rockets of different types, some would explode in midair and rain shrapnel, others would set fires, and a particularly annoying type would snake along the ground and stab people in the dick.
Modern Era
World war 1 World War 2 Cold war Drones and MLRS today
On the Tabletop
Warhammer 40k
See: Imperial Guard, a faction that can only be described as "How Many Artillery Pieces Can I Afford?" Infantry can take Mortars, Lascannons, or Missile Launchers, while you have not one, not two, not even three, but FOUR types of indirect artillery vehicles, with that last one being a A motherfucking Nuclear Missile. And they just got a new option in the form of Field Ordnance Batteries, letting you relive the PTSD dreams of an American infantryman whose FOB just got hit by the Taliban but IN SPESS.
Sure, Baneblades and Conscript Spam are more iconic of the faction, but that's mostly because of how unfun it is to both play and play against someone that goes all in on artillery, with pieplate blast templates or indirect fire spam from 3 units of 3 model artillery.
Space Marines can only wish they were this cool, but they instead have to rely on Missiles guided by the remains of failed Initiates, or derpy multi-barreled missile launchers instead.