In computer science, the ambient calculus is a process calculus devised by Luca Cardelli and Andrew D. Gordon in 1998, and used to describe and theorise about concurrent systems that include mobility. Here mobility means both computation carried out on mobile devices (i.e. networks that have a dynamic topology), and mobile computation (i.e. executable code that is able to move around the network). The ambient calculus provides a unified framework for modeling both kinds of mobility. It is used to model interactions in such concurrent systems as the Internet.