REBOL, the Relative Expression Based Object Language (pronounced ['rebl]), is a data exchange and programming language designed specifically for network communications and distributed computing. Its designer, Carl Sassenrath, calls it a 'messaging' language, and says this about it: "The main idea of REBOL is that it gets used for: server, client, communications between them, and storage on them. The power of REBOL comes from its unique integration of programming language concepts and meta-data language concepts.