This paper by Bill Mark et. al describes the Cg high-level graphics hardware programming language and the associated run-time system. The paper details the rationale behind the decisions made in the design of the language. (Cg: A system for programming graphics hardware in a C-like language. Bill Mark, R. Steven Glanville, Kurt Akeley, and Mark J. Kilgard. To appear in the proceedings of SIGGRAPH 2003.)