Definition: "OSIery" is a term that refers to the concept of a hierarchical model used in computer networks, data communication systems, and other applications. It was first defined by the International Organization for Standardization (ISO) in 1974 as part of its ISO/IEC 8702:1974 standard for defining OSI protocols. The OSI model is based on four levels of structure: Application Layer, Data Link Layer, Network Layer, and Transport Layer.