A First Lieutenant is a military rank typically found in the army, air force, and marine corps. It is usually above the rank of Second Lieutenant and below the rank of Captain. First Lieutenants often serve as leaders of small units and are responsible for training and managing soldiers, ensuring that missions are carried out effectively. In many countries, the rank of First Lieutenant is denoted by a specific insignia, such as silver bars or a single star. This rank is important for career progression, as it often leads to higher leadership positions within the military structure, contributing to overall operational success.