OSI networking model

Layer	What It Does
Application Layer	The application layer is what the user of the computer will see and interact with. This layer is the "Application" that the programmer develops.
Presentation Layer	The Presentation Layer is involved in formatting the data into a human-readable format, and translating different languages, etc...
Session Layer	The Session Layer will maintain different connections, in case a single application wants to connect to multiple remote sites (or form multiple connections with a single remote site).
Transport Layer	The Transport Layer will handle data transmissions, and will differentiate between Connection-Oriented transmissions (TCP) and connectionless transmissions (UDP)
Network Layer	The Network Layer allows different machines to address each other logically, and allows for reliable data transmission between computers (IP)
Data-Link Layer	The Data-Link Layer is the layer that determines how data is sent through the physical channel. Examples of Data-Link protocols are "Ethernet" and "PPP".
Physical Layer	The Physical Layer consists of the physical wires, or the antennas that comprise the physical hardware of the transmission system. Physical layer entities include WiFi transmissions, and 100BaseT cables.