With the introduction of computers occurring more than 50 years ago, automation systems have become more powerful, comprehensive, and complex. The key to handling this complexity was the introduction of many aspects, including architecture models that structure and standardize functions, information, and its exchange; procedures; and the interaction of subsystems. With the recent Industry 4.0 and industrial Internet of Things (IIoT) movements, such models have received fresh attention and have grown in complexity. This article reviews the evolution of automation models. It compares several recent approaches, their standardization, and recent computing paradigms, and discusses their practical use and importance for modern automation systems.