system Anything we choose to regard (a) as a whole and (b) as comprising a set of related components. More formally a system S = (C, R), where C is the set of its components and R is the set of relationships (or interfaces) that combine them into a coherent whole. In computing the word is freely used to refer to all kinds of combinations of hardware, software, data and other information, procedures, and human activities. An airline reservation system, for instance, comprises all those things, distributed and connected worldwide. At the other end of the spectrum, an *operating system just comprises software components.