Key Takeaways

There are seven layers to the OSI model:

Physical
Data Link
Network
Transport
Session
Presentation
Application

Data from the sender travels from layer 7 to layer 1.
Data to the recipient travels from layer 1 to layer 7.

OSI Model vs. TCP/IP Model

A Layered Approach to Networking

Both the OSI Model and TCP/IP Model attempt to explain computer networking in layers. This abstraction helps to makes it easier to develop protocols and standards at various stages of computer networking. It also makes it easier to troubleshoot issues when they arise, as the flow of data through the layers can be more easily dissected.

Differences Between the Two Models

TCP/IP was developed in the 1970s
OSI was developed in the 1980s
TCP/IP has four layers
OSI has seven layers

The OSI model further abstracts protocols into seven layers to make development and troubleshooting easier. It is much easier for humans to break complicated processes down into smaller sub-steps. In the OSI model, protocols are fit inside specific layers. With TCP/IP, the layers were developed after the protocols.