How many layers are there in the OSI model?

The OSI (Open Systems Interconnection) model consists of seven layers, which provide a framework for understanding and implementing network protocols and communications. These layers are:

1. Physical Layer - Responsible for the transmission of raw bit streams over a physical medium.

2. Data Link Layer - Handles error detection and correction from the physical layer and provides node-to-node data transfer.

3. Network Layer - Manages routing and forwarding of data packets, addressing, and establishing paths between devices.

4. Transport Layer - Ensures complete data transfer, error recovery, and flow control for applications.

5. Session Layer - Manages sessions between applications, handling the opening, closing, and managing of sessions.

6. Presentation Layer - Translates data between the application layer and the network, including data format translation and encryption/decryption.

7. Application Layer - Provides network services to end-user applications and manages the communication between software applications and the network.

Understanding the seven layers and their distinct roles helps in diagnosing network issues, designing protocols, and improving interoperability between diverse systems. The framework outlines how data should be sent and received over a network, making it pivotal in network design and troubleshooting.