An armory (US spelling) or armoury is a place where arms and ammunition are made, maintained and repaired, stored, issued to authorized users, or any combination of those. Over the centuries, this has included every variant of such a place, whether privately or publicly owned (with the latter in older royal and modern state-owned versions).

Armories and arsenals are both places where arms or ammunition may be made, maintained and repaired, stored, or issued. The usage differences between the names is mainly a matter of historical linguistic development. It is a common principle in natural language that synonyms have subtle connotative boundaries (albeit ones that may be somewhat permeable over time and distance).

Today an armory is typically a military depot used for the storage of weapons and ammunition. The term may also apply to an area within a building used for the storage of weapons. In a typical armory, ammunition is stored separately from weapons (both under lock and key) to minimize the potential for misuse, theft, and safety breaches. Very sensitive alarm systems are also extensively used.

Sub-armory is a term for a temporary storage of weapons and ammunition. A sub-armory could be operational with an officer on duty or un-operational with officers utilizing the area as duty dictates. A sub-armory could also be any temporary Post where an officer might be armed and on duty but could also be relieved of that duty and of their weapons and ammunition (example: A Surveillance Tower or patrol vehicle which is only operational certain times of the day. The first officer of the day attains the weapons and ammunition, taking these items to the Post, and then officers relieve each other until the last officer of the day returns these items to the armory).