represent a principle of hierarchical structuring.
1 This principle is frequently used in the field of communication technology. A layer provides services for the superordinate layer using the services of the subordinate layer. The best-known representatives are the ISO/OSI 7-layer model and the TCP/IP reference model. – 2. three-tier model (three-tier architecture), see also supplier pyramid – 3. see three-tier software architecture

Source: logipedia / Fraunhofer IML