From early on, visual management (VM) has been an intrinsic ingredient of the Toyota Production System (TPS) and its derivatives like lean production. Akin to the evolution of most other parts of the TPS, it has been developed through practitioner efforts rather than being propelled by theoretical insights. Recently, scholars have started to create a theoretical knowledge base for VM. Besides taxonomies of visual devices and their functions, there is only one fully fledged theory of VM, based on the concept of affordance. It is contended here that the scholarly field of visual management has been too narrowly defined. In fact, research on (or bearing on) visual devices has been carried out in several other, mostly small fields, often with little mutual awareness. A review on the theoretical explanation of VM is provided, based on this wider literature. The concept of affordance has been used in this context already in early 1990s. This focuses attention especially to the human cognitive capabilities and corresponding features of visual devices. Generally, VM is argued to provide a more rapid and reliable mode of communication in comparison to traditional alternatives. VM is thus compatible with the lean tenets of time compression and variability reduction. This explains its central role in lean production.