Open Shading Language (OSL) is a shading language developed by Sony Pictures Imageworks, a Canadian visual effects and computer animation studio headquartered in Vancouver, British Columbia and Montreal, Quebec, with an additional office on the Sony Pictures Studios lot in Culver City, California, a unit of Sony Pictures Entertainment's Motion Picture Group, which through an intermediate holding company called Sony Film Holding Inc., it is operated as a subsidiary of Sony Entertainment Inc., which is itself a subsidiary of the Japanese multinational technology and media conglomerate Sony Group Corporation, for use in its Arnold Renderer.

[6] 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.

SIMD Batch shader Mode and OptiX support are in development and experimental.

We explained a lot of the details about the new ideas in this SIGGRAPH 2010 talk 'Open Shading Language'.

[10] And apparently, the rest of the industry agreed, because it resulted in an 2017 Academy technical achievement award.