Autonomous underwater vehicles is a multidisciplinary research domain concerned with the design, development, control, and deployment of untethered robotic systems capable of autonomous operation in submerged environments. This field investigates fundamental challenges in underwater navigation without global positioning, robust sensing and perception in acoustically and optically complex media, energy efficiency for prolonged endurance, and intelligent decision-making for tasks ranging from scientific data collection and environmental monitoring to infrastructure inspection and resource exploration. Its significance lies in enabling access to and persistent presence within marine and aquatic depths that are hazardous, remote, or prohibitively expensive for human intervention or traditional tethered systems.