The Open Systems Interconnection model (OSI model) is a concept that describes computer system communications using seven (7) layers of abstraction.
| Layer No | Layer Name | Mnemonic Device |
|---|---|---|
| 1 | Physical | Please |
| 2 | Data Link | Do |
| 3 | Network | Not |
| 4 | Transport | Throw |
| 5 | Session | Sausage |
| 6 | Presentation | Pizza |
| 7 | Application | Away |
Wikipedia article on the OSI model.