OSI Layers and Definitions
The OSI layers are defined as follows:
Layer 1: Physical
Layer 2: Data link
Layer 3: Network
Layer 4: Transport
Layer 5: Session
Layer 6: Presentation
Layer 7: Application
The four lower layers (called the data flow layers)
define connection protocols and methods for
exchanging data.
The three upper layers (called the application layers)
define how the applications within the end stations
communicate with each other and with users.
Several mnemonics have been developed to help you
memorize the layers and their order. Here’s one:
Please Do Not Throw Sausage Pizza Away