The Strouhal Number (St) is a dimensionless quantity used in fluid dynamics to describe oscillating flow mechanisms. It is defined as the ratio of inertial forces to the elastic forces in a fluid, typically expressed as St = fL/U, where f is the frequency of oscillation, L is a characteristic length, and U is the flow velocity. This number helps characterize the behavior of various fluid systems, such as those found in aerodynamics and hydrodynamics. In practical applications, the Strouhal Number is important for understanding phenomena like vortex shedding, which occurs when fluid flows past a bluff body, creating alternating low-pressure zones. Engineers and scientists use this number to predict the performance of structures like bridges and buildings in wind or water flow, ensuring stability and safety in design.