Why are there 7 networking layers instead of 5 in the OS?

Answer 1

Please Do Not Throw Sausage Pizza Away

Application - email..telnet...ftp layer
Presentation - encryptian layer
Session - establish, manage, terminate connections between apps.
Transfer - end to end error recovery and flow control
Network - switching/routing, IP address
Data Link - encode/decode into bitsMAC address layer
Physical - bit stream (electrical pulses, light, or sound signal)

These are the 7 layers. I am not sure where you got 5. This is the correct order as well.

Answer 2

I think you mean the OSI model? What 5 were you expecting?
Why do you think it should be 5 instead of 7? It's just someone's representation. One idea that has caught on.