Large bore diameter (nominally 3" or greater) firearms designed to be operated by a crew of individuals. They are utilized to project explosive, armor defeating, incendiary, or nuclear projectiles over great distances. They are normally moved by vehicle because of their size and weight. "Cannon," mortars, howitzers, and similar are considered artillery.
Artillery is a weapon of war that operates by projection of munitions far beyond the effective range of personal weapons. Artillery comprise specialised devices which use some form of stored energy to operate, whether mechanical, chemical, or electromagnetic. Originally designed to breach fortifications, they have evolved from nearly static installations intended to reduce a single obstacle to highly mobile weapons of great flexibility in which now reposes the greater portion of a modern army's offensive capabilities.