What is the OSI Model?

The OSI (Open Systems Interconnection) model is a 7-layer conceptual framework created by the ISO to standardize how different computer systems communicate over a network. It breaks the communication process into distinct layers, so hardware and software from different vendors can interoperate.

The 7 Layers (bottom to top):

1. Physical – Transmits raw bits over a physical medium (cables, radio waves, etc.)
2. Data Link – Organizes bits into frames; handles MAC addressing and local error detection (e.g., Ethernet, Wi-Fi)
3. Network – Handles routing and logical addressing across networks (IP addresses, routers)
4. Transport – Ensures reliable (TCP) or fast (UDP) end-to-end data delivery
5. Session – Establishes, manages, and terminates communication sessions
6. Presentation – Translates data format, handles encryption and compression
7. Application – Where end-user applications interact with the network (HTTP, FTP, DNS)

Mnemonic: Please Do Not Throw Sausage Pizza Away

For a more detailed breakdown, you can check out this explanation here: https://conceptofosimodel.blogspot.com/