The Open Systems Interconnection (OSI) model is a conceptual framework that standardizes and describes the functions of a networking system. It breaks down the complex communication process between computer systems into seven distinct layers, each with its own specific functions and protocols.

The seven layers of the OSI model are given below:

Physical Layer (Layer 1): This layer deals with the physical transmission of data over a network medium, such as cables or wireless signals. It defines the electrical and mechanical specifications for sending and receiving data bits.

Data Link Layer (Layer 2): This layer is responsible for organizing data into frames and ensuring reliable transmission between two directly connected devices. It handles error detection and correction, as well as media access control (MAC) addressing.

Network Layer (Layer 3): This layer handles routing and forwarding of data packets across multiple networks. It defines logical addressing (IP addresses) and determines the best path for data to travel from source to destination.

Transport Layer (Layer 4): This layer provides end-to-end communication between applications on different hosts. It ensures reliable data delivery, manages data segmentation and reassembly, and controls flow control and congestion management.

Session Layer (Layer 5): This layer establishes, manages, and terminates communication sessions between applications. It coordinates dialog control, synchronization, and authentication.

Presentation Layer (Layer 6): This layer handles data formatting and translation for compatibility between different systems. It deals with data encryption, compression, and character encoding.

Application Layer (Layer 7): This layer provides the interface between user applications and the network. It defines protocols for common network services such as email, file transfer, and web browsing.

The OSI model serves as a reference model for understanding and designing network protocols and architectures. It provides a common language and structure for network engineers and developers to communicate and collaborate effectively.