Boundary-layer stability refers to the study of the behavior of the thin layer of fluid adjacent to a solid surface, known as the boundary layer, and how it can become unstable and develop into turbulence. This area of research is important in understanding the flow of fluids over surfaces, such as in aerodynamics, meteorology, and oceanography. By studying boundary-layer stability, researchers can predict when and how turbulence will develop in a fluid flow, which is crucial for designing more efficient vehicles and structures. Methods used in this research area include linear stability analysis, non-linear simulations, and experimental techniques. Overall, boundary-layer stability research plays a crucial role in various engineering and scientific fields where the understanding and control of fluid flow dynamics are essential.