Open Shading Language (OSL) is a shading language developed by Sony Pictures Imageworks for use in its Arnold Renderer. It is also supported by the Cycles render engine in Blender (starting with Blender 2.65)and V-Ray 3. OSL's surface and volume shaders define how surfaces or volumes scatter light in a way that allows for importance sampling; thus, it is well suited for physically-based renderers that support ray tracing and global illumination.