The OSI (Open System Interconnection) model is a conceptual framework that standardizes the functions of a communication system into seven distinct layers. These layers, abbreviated as P, D, N, T, S, P, A, represent the Physical, Data Link, Network, Transport, Session, Presentation, and Application layers, respectively. Each layer performs specific tasks to facilitate data transmission across a network.

Key Points:

1. Physical Layer (P): Handles the physical transmission of data over the network medium, such as cables and wireless signals.
2. Data Link Layer (D): Ensures reliable transmission of data frames between adjacent nodes on the same network segment.
3. Network Layer (N): Manages routing and forwarding of data packets across different networks.
4. Transport Layer (T): Provides end-to-end communication services, ensuring reliable data delivery between hosts.
5. Session Layer (S): Establishes, manages, and terminates connections between applications.
6. Presentation Layer (P): Translates data from the application layer into a format that can be understood by the network.
7. Application Layer (A): Interacts directly with the end-user applications, facilitating network services like email, web browsing, and file transfer.

Summary:

The OSI model’s seven layers, abbreviated as P, D, N, T, S, P, A, offer a structured approach to network communication. Understanding these layers is crucial for network design, troubleshooting, and ensuring interoperability between different network devices and protocols.