OSI is an acronym for Open Systems Interconnection. The International Organization for Standardization (ISO) founded it in 1984 and It is a seven-layer architecture with separate functions for each tier. These seven layers work together to transport data across the globe from one person to another.

• Physical Layer: In the OSI reference model, the physical layer is the lowest layer. It is responsible for establishing a physical link between the devices. The physical layer stores bits of information. Its JOB is to send individual bits from one node to the next. This layer receives data and turns it into 0s and 1s before sending it to the Data Link layer, which reassembles the frame.
• Data Link Layer: The data link layer is in charge of message transport from one node to the next. This layer's primary function is to ensure that data transfers between nodes via the physical layer are error-free. The Data Link Layer is divided into two sublayers:
  • Control of Media Access (MAC)
  • Control of Logical Links (LLC)
• Network Layer: The network layer is in charge of data transfer between HOSTS that are linked to different networks. It also manages packet routing, which is the process of selecting the shortest path among a vast number of alternatives to send a packet. The SENDER and receiver's IP addresses are INCLUDED in the header by the network layer.
• Transport Layer: The transport layer provides services to the application layer, whereas the network layer provides services to the transport layer. In the transport layer, segments are the data units. It is in charge of delivering the entire message from start to finish. The transport layer recognises successful data transmission and re-transmits the data if a mistake is found.
• Session Layer: The Session Layer is responsible for creating connections, maintaining sessions, authenticating users, and guaranteeing security.
• Presentation Layer: The data from the application layer is obtained and processed in this layer so that it may be delivered across the network in the correct format.
• Application Layer: The Application layer is at the very top of the OSI Reference Model stack of layers, and it is implemented by network applications. These applications generate the information that must be transmitted via the network. This layer also serves as a window through which application services can connect to the network and display information to the user.