A deck gun or a ship's gun is a term commonly used to describe a large artillery piece mounted on the deck of a naval vessel. Some of the synonyms for the term deck gun include naval gun, warship cannon, battleship firearm, and ship's cannon. These guns are typically mounted on the upper deck of a vessel and used for offensive purposes when port facilities are not available. The size and weight of these guns depend on the type of vessel they are mounted on, with larger ships boasting more powerful and larger guns to engage bigger targets. However, with the rise of guided missile technology, deck guns have become less common on modern-day naval vessels.