This brief pal)er intro(htces a small anonynmus formal system representing the core theory of concurrent object-based computing. Milner's 1r-calculus is its underlying formalism, but the original calculus is reinterpreted and reformulatcd to become a simple and powerful expression of concurrent object-based computing. We briefly dcscribe its underlying computational framework, its syntax, transition rules, semantic equivalcllcc, and its special properties concerning "naming", which makes this calculus unique among various concurrency formalisms.