The OSI (Open Systems Interconnection) model facilitates network communication by providing a standardized framework that enables diverse systems to communicate over a network. It consists of seven layers, each with specific functions that interact with the layers directly above and below them.

Layers and Functions:
1. Physical Layer: Transmits raw bitstreams over a physical medium (e.g., cables, radio waves).
2. Data Link Layer: Manages node-to-node data transfer and error detection/correction (e.g., Ethernet).
3. Network Layer: Handles data routing, forwarding, and addressing (e.g., IP).
4. Transport Layer: Ensures end-to-end communication, error recovery, and flow control (e.g., TCP, UDP).
5. Session Layer: Manages sessions and controls dialogues between computers (e.g., NetBIOS).
6. Presentation Layer: Translates data formats, encryption, and compression (e.g., SSL/TLS).
7. Application Layer: Interfaces directly with user applications, providing network services (e.g., HTTP, FTP).

Facilitation of Communication:
Interoperability: Ensures different hardware and software systems can communicate.
Modularity: Each layer operates independently, simplifying troubleshooting and development.
Standardization: Provides universal guidelines for hardware and software developers, promoting compatibility and innovation.
Layer Interaction: Each layer only communicates with its adjacent layers, ensuring a structured and organized approach to data transmission.

By delineating these functions, the OSI model ensures efficient, reliable, and scalable network communication across diverse systems and technologies.