Elements are defined as minimum parts that cannot be divided any more. Are elements of material systems atoms and those of information systems bits?

The word system is derived from a Greek word sunistanai (to combine) and a system is usually defined as a group of combined elements. This definition identifies system/element relation with that of whole/part, but a system is not just a whole composed of parts, much less spatial subsumption relation between a whole and parts. What is a system, then?