Networking is a vast topic that, like everything, starts with the basics. OSI - Open Systems Interconnection model is used to understand network interactions as seven structured layers. Each layer serves a specific function and communicates with the layers directly above and below it, creating a stack that efficiently handles communications from one end to another.

Here's a brief overview of each of the seven layers:

1. Physical - Equipment involved in data transfer, such as cables, switches, and the electrical impulses that traverse these media.
2. Data Link - Responsible for node-to-node data transfer and error detection in frames. Protocols like Ethernet and PPP operate at this layer.
3. Network - Manages device addressing, identifies the best paths for data transfer, and handles packet routing. IP (Internet Protocol) is a key protocol at this layer.
4. Transport - Ensures complete data transfer with mechanisms for error recovery and flow control. Protocols like TCP and UDP operate here.
5. Session - Manages sessions between applications. Continuous exchange of data between two nodes.
6. Presentation - Translates data between the application layer and the network. It ensures data is in a usable format and performs encryption, compression, and other transformations.
7. Application - The closest to the end user, dealing with application services for file transfers, email, and other network software services like HTTP.

How can I use it?

OSI model explains how different pieces of network fit together by making this layers distinction. It can help with practical networking scenarios like:

• Troubleshooting: By understanding layers in networking, it can be easier to identify and resolved issues.
• Network Design: Design more efficient and secure networks by knowing which functionalities belong to which layers.

This model is a very theoretical approach to networking, but nevertheless crucial in understanding, designing and troubleshooting networks.

That's all for today. Quick and brief!