Projectile (early on with shot and then later on with shells) and powder charge are loaded via the muzzle and rammed down the barrel, and then fired at the target.
Muzzle-loading artillery came in smoothbore and rifled form, the rifled guns increasingly taking over from the smoothbores as time past and technology improved.
Most were made of bronze because of a lack of metallurgic technology, but cast and wrought-iron guns were common as well, particularly later on.
Muzzleloading artillery evolved across a wide range of styles, beginning with the bombard, and evolving into culverins, falconets, sakers, demi-cannon, rifled muzzle-loaders, Parrott rifles, and many other styles.
Handcannons are excepted from this list because they are hand-held and typically of small caliber.