OSI may refer to any of the following:
1. Short for Open System Interconnection, OSI is a network model developed by ISO in 1978 where peer-to-peer communications are divided into seven layers. Each layer performs a specific task or tasks and builds upon the preceding layer until the communications are complete. Below are the purposes of each of the seven layers.
Tip: The seven layers in the OSI model are usually displayed in reverse order, with layer 7 listed first (at the top) and layer 1 listed last (at the bottom).
1 - Physical layer - responsible for the electrical, mechanical, and timing across the link.
2 - Data link layer (also known as the link layer) - responsible for transmitting data across a link.
3 - Network layer - responsible for routing information through the network and allowing systems to communicate.
4 - Transport layer - responsible for transferring information between endpoints on the network and deals with errors such as lost or duplicate packets.
5 - Session layer - responsible for managing a session between two applications.
6 - Presentation layer - responsible for the data formatting and display, allowing for compatibility.
7 - Application layer - responsible for user interaction. An example of an OSI application is the FTAM.