This document outlines the 7 layers of the OSI model from top to bottom - Application, Presentation, Session, Transport, Network, Data Link, and Physical layers. Each layer controls certain aspects of communications and data transmission with the highest layers focusing on software and applications and the lower layers focusing on hardware and physical connections.

2. OSI
(Header)
(Application Layer)

3. (Text)
(Presention Layer)

4. (Header)
(Session Layer)

5. (Host-to-Host)
(End-to-
End)
( )
(Address)
(Checksum)
(Transport Layer)

6. -
(Network Layer)

7. (Checksum)
ACK (Acknowledge)
ACK
(Data Link Layer)

8. -
RS- -C (PIN)
(Physical Layer)