Fluid mechanics is the branch of physics that studies the behavior of fluids, which include liquids and gases, both at rest and in motion. It examines how these substances interact with forces and their surroundings, helping to understand phenomena like airflow, water flow, and pressure changes. This field is essential in various applications, from designing aircraft and ships to predicting weather patterns and understanding natural processes like ocean currents. Fluid mechanics combines principles from thermodynamics and continuum mechanics to analyze and solve problems related to fluid behavior in different environments.