Ammunition usually refers to the all the types of bullets which are being shot from different weapons, like guns, pistols, machine guns, cannons but also more ancient weapons like bows, crossbows, catapult etc. In most cases these bullets can be used only one time and also include missiles and rackets.
Modern ammunition is usually built from a bullet which is fired from firearm using the gases which are created in the process of the exploding explosive. This explosive is found in the shell which is connected to the bullet. The shell and the bullet together are called Cartridge. These two can be loaded to the barrel separately. These bullets come in different types according to their different goals: to kill a specific individual, to spread damage or shrapnel, to go through armor, to start a fire etc.
Ammunition is usually divided into bullets for small arms, hand grenades, shells for cannons, shells for tanks, artillery shells, mortar shells, aircraft bombs, missiles, rackets, smart bombs etc. Ammunition and food and water is what creates the huge dependency of armed forces on logistics. And for that you need warehouse, production ability, transportation lines and vehicles and many many other solutions. Because of the dangoures character of these materials the storage of it is very challenging and requires guarded places from enemies and fire or other damage. This is usually achieved in well-kept bunkers, also another challenge is the way you treat ammunition which is overdue and can’t be used in battle.