The OSI (Open Systems Interconnection) model is a fundamental framework for understanding network architecture. It organizes a complex system into seven distinct layers, with each layer responsible for different networking protocol tasks. These layers communicate by exchanging Protocol Data Units (PDUs) and are commonly referred to by name or number (1-7).

1. The Physical Layer: This layer is responsible for the transmission of the raw bitstream over a physical medium. It involves the translation of bits into electricity, light, or radio signals and controls their transmission rates.
2. The Data Link Layer: This layer divides data into frames for transmission at the physical layer and manages connections between nodes.
3. The Network Layer: Expanding the focus from point-to-point links to interconnected nodes within a network, this layer is responsible for routing traffic based on IP addresses.
4. The Transport Layer: This layer ensures the accurate transmission of data between nodes, including error correction and sequencing.
5. The Session Layer: Responsible for managing sessions between nodes, this layer deals with session setup, authentication, termination, and reconnections.
6. The Presentation Layer: This layer translates network data into formats expected by applications, handling data encodings and encryption.
7. The Application Layer: Including protocols designed for end-users, such as HTTP for data transmission, this layer serves as the interface for user interactions.

The OSI model provides a theoretical framework that aids in understanding network architecture, although not mandatory for modern networking protocols.

In addition, there is another networking model called the TCP/IP Model, which came before the OSI Model and closely matches the protocols used in network security. TCP/IP stands for Transmission Control Protocol/Internet Protocol. This protocol consists of standardized rules that enable computers to communicate on a network.

The TCP/IP consists of four layers:

• Application Layer: This single layer maps to the Application, Presentation, and Session layers of the OSI model. Some protocols that operate at this layer include HTTP, SMTP, and DNS.
• Transport Layer: This layer maps to the Transport layer of the OSI model. TCP and the User Datagram Protocol (UDP) operate at this layer.
• Internet Layer: The Internet layer is equivalent to the Network Layer in the OSI model. This layer is primarily covered by the Internet Protocol (IP), but ARP, IGMP, and ICMP also operate at this layer.
• Network Access Layer: This layer combines the Physical and Data Link layers from the OSI model. Ethernet, Token Ring, ATM, and Frame Relay are examples from the TCP/IP Protocol Suite that operate at this layer.

The OSI model is more theoretical, describing the various tasks that must be accomplished to enable application-layer data to be transmitted via electricity, light, or radio waves. The TCP/IP model is more practical and maps closely to actual network protocols.

Understanding the OSI Model has several advantages. It provides a mental model of how networking works and the different functions involved in enabling network communication. This model makes troubleshooting issues easier to solve, as it depends on various functions and networking protocols. Additionally, it helps explain if a data breach or unauthorized hack has occurred.

In conclusion, the OSI model is essential in theory to comprehend the functioning of a network and the role each layer plays in network security. Information technology is constantly evolving and adapting to the new demands of business and education. Therefore, new protocols, functions, and technologies will come into fruition.