Tell us about the OSI model layers.

The OSI (Open Systems Interconnection) model describes the structure of a network and divides its functions into seven layers of abstraction:

1. Physical Layer: Responsible for transmitting bits over a physical medium (cable, fiber optics, radio waves). Defines electrical, mechanical, and procedural characteristics of the interface.
2. Data Link Layer: Ensures reliable data transfer between neighboring nodes. Handles MAC addressing, error detection and correction, and flow control.
3. Network Layer: Responsible for routing packets from sender to receiver across the network. Works with IP addresses and determines the optimal path.
4. Transport Layer: Provides reliable or unreliable data transfer between end processes. Manages data segmentation, error control at endpoints, and flow control. Protocol examples: TCP (reliable), UDP (unreliable).
5. Session Layer: Manages communication sessions between applications, establishing, maintaining, and terminating them. Handles synchronization and dialogue between nodes.
6. Presentation Layer: Responsible for data representation in a format understandable by the application layer. Performs data transformation, encryption/decryption, and compression.
7. Application Layer: Provides network services to end users and applications. Protocols like HTTP, FTP, SMTP operate here.