The document discusses the OSI model, which structures network communication into 7 layers - physical, data link, network, transport, session, presentation, and application. It provides an overview of the functions of each layer, from the physical layer which transmits raw data up to electrical signals, to the application layer which provides services for file transfers, printing and other applications. Diagrams and examples are included to illustrate how data moves through each layer of the OSI model during network communication.