Our ever advancing abilities to examine nanosize metals and/or oxides with atomic and/or high temporal resolution have recently started to reveal much that is new about the behaviour of such systems. In many cases the notion of passive entities, upon which catalytic events occur, has been overturned, and with it many ideas that for a long time were axiomatic to the understanding of their behaviour. In its place a world of structuro-reactive dynamism is starting to appear wherein the atomic scale structure and reactivity are intimately tied to the nature of the environment being experienced. The aim of this tutorial review is to introduce the reader to these phenomena, to discuss how we might observe and categorise differing types of dynamic change, and to give some specific examples of where and how this fundamental structural dynamism can be tangibly linked to the reactive behaviour of heterogeneous catalysts.