a vertical stack that consists the following 7 steps:
1.Physical: this layer conveys the bit stream-electrical impulse, light, or radio signal, through the network at the electrical and mechanical level.
2.Data Link: this layer furnishes transmission protocol knowledge.
3.Network: this layer provides switching and routing technologies, creating paths for transmitting data from node to node.
4.Transport: this layer provides transparent transfer of data between end systems, or hosts, and is responsible for end-to-end error recovery and flow control.
5.Session: This layer establishes, manages and terminates connections between applications.
6.Presentation: this layer provides independences from differences in data representation.
7.Application: this layer supports application and end-user processes.
