Brillouin Scattering, Volume 109 in the Semiconductors and Semimetal series, marks the centenary of Leon Brillouin’s seminal 1922 paper which provided a detailed theory of the effect that now bears his name. Stimulated Brillouin Scattering (SBS) is the strongest third order optical nonlinearity and plays an important role in contemporary science and applications, particularly lasers, communications, and fibre optics, as well as playing a new role in experimental physics and the life sciences. This volume provides a foundational perspective on Brillouin scattering, starting with a historical review of Brillouin scattering, the theory of SBS and the convergence between SBS and Optomechanics. We then consider SBS in several different waveguide geometries, including photonic crystal fibres, integrated optics and superfluids.