A First Lieutenant is a military rank typically found in the armies, navies, and air forces of various countries. In the United States Army, for example, a First Lieutenant is above a Second Lieutenant and below a Captain. This rank usually indicates that the officer has gained some experience and is often responsible for leading a platoon or serving as a staff officer. In the U.S. Navy, a First Lieutenant is a title given to a senior officer on a ship, responsible for the deck and its operations. This role is crucial for maintaining safety and efficiency during naval missions. The rank is also present in other military branches, reflecting a similar level of responsibility and leadership.