Many engineering systems involve flow over solid surfaces, where surface characteristics strongly influence performance. Roughening the surface generally produces more entropy due to an increase in friction. This chapter first presents the fundamentals of flow over a surface and the mechanisms by which roughness alters momentum transfer and energy dissipation. It then elucidates surface texturing, an innovative surface manipulation for lowering friction and improving overall system efficiency. The underlying flow physics invokes slipping at the surface. With nature excelling in harnessing fluid slipping to strive, this chapter concludes with a highlight of the state-of-the-art biomimetic strategies, where inspiration from biological systems guides the design of advanced textured surfaces.