<p>Isomerization—the coherent transformation of a material from one atomic structure to another while preserving its composition and total number of atoms—is well understood in organic chemistry. Only recently has this phenomenon been identified in inorganic nanoclusters. The underlying mechanisms and structural relationships responsible for inorganic isomerization, however, remain largely unexplored. Addressing this gap is crucial not only for advancing fundamental science but also for enabling new applications and technologies. Here, we introduce the concepts and historical context of isomerism and isomerization, define key terminology and distinguishing characteristics of these phenomena, and review real-world examples of inorganic isomerization in both metallic and semiconductor clusters. We compare these two material classes of isomerizations, examine their initiation and structural changes, discuss the role of size, and consider the future possibilities for inorganic isomerization. Finally, we present our conclusions and outlook for this emerging field.</p> Graphical Abstract <p></p>