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Tip Thursday: Internet 101

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By David Perera March 29, 2007

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Every Thursday, Tech Insider brings computing tips and basic computing info you can put to use right away.

This week: introducing and remembering the OSI Model.

OSI is short for Open Systems Interconnection and is the basic reference for discussing how the Internet works; anybody who uses the Web should at least be aware of it.

Think of the Internet as a seven-layered cake (as opposed to, say, a "series of tubes"). At the bottom layer are the actual physical things enabling your connection -- wires and such.

At the very top are the protocols for things like e-mail and the Web; this is known as the application layer. These applications are not the same as applications as you probably think of them normally, things like Microsoft Word or Excel. (Computer scientists have an annoying predilection for using the same name to describe multiple things.)

Anyway, in between the applications and the physical layer are five other very important sections; from top to bottom, the layers are as follows: presentation, session, transport, network, and data link. Read more about them here.

How do you make all these layers stick in your mind? Try this handy mnemonic device:

People Don’t Need To See Paula Abdul.

How’s it work? Easy: Physical, Data link, Network, Transport, Session, Presentation, Application.

For a more detailed look at networking basics, see this Cisco paper.

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