Seven layers of the OSI Model
Computing   Wikipedia  
There are many mnemonics for the seven layers of the OSI Model in computing. Physical / Data Link / Network / Transport / Session / Presentation / Application. Because the layers are numbered from the bottom-up, many mnemonics have been developed in both directions, from the top down and from the bottom up:

 Mnemonic:
People Desperately Need To See Pamela Anderson.

 Mnemonic:
Please Do Not Throw Sausage/Salami Pizza Away - starts at layer 1 (the bottom),

 Mnemonic:
Programmers Like Networks That Seldom Postpone Anything.

 Mnemonic:
Starting from layer 7: All People Seem To Need Data Processing.