Layers of the OSI model and their functions
Application processes reside outside the OSI system and use the communication services provided by it
7. Application layer acts as an interface between the application process and the telecommunications world
6. Presentation layer negotiates a transfer syntax and performs transformations between the local and transfer syntax
5. Session layer provides organized and synchronized data transfer to the presentation layer
4. Transport layer raises the service provided by the network layer to the level required by the session layer providing reliable end-to-end transport service
3. Network layer is responsible for routing messages through the network
2. Data Link layer transfers data between two neighboring nodes forming frames out of bits, it may also perform flow and error control
1. Physical layer tranfers bits (and possibly non-data symbols) over the physical media from one network node to another
Physical media (such as copper cable, optical fiber or the ”ether”) act as the medium through which information is transferred