Application Layer

Provides interface between software applications and network for interpreting applications' requests and requirements

Presentation Layer

Allows hosts and applications to use a common language; performs data formatting, encryption and compression

Session Layer

Establishes, maintains and terminates user connections

Ensures accurate delivery of data through flow control and segmentation and reassembly, error correction and acknowledgement

1.  Transfers data between adjacent between nodes on any given Local Area Network.

2.  Provides the procedural means to transfer data between network entities and sometimes to detect and correct errors that have occurred within the Physical Layer.

3.  This layer's frames do not cross the boundaries of a local network segment and instead focus on local delivery, addressing, and media arbitration.

• Manages signaling to and from physical network connections.

• It does not try to interfere with, encode/decode, or otherwise logically manipulate the signal. 

• The layer of low-level networking equipment, such as some hubs, cabling, and repeaters .

• Never concerned with protocols or other such higher-layer items.