It can apply to you if you -- for example -- have an "always on" internet connection (a static IP number and a cable modem of DSL or similar link that doesn't have to be "dialed up" to be activated. In that case your machine is just any other always-present server on the Internet, and its IP number could become the target of a hack, conceivably. And conceivably, one way to reduce that risk would be to find and install a firewall software package that would prevent hackers from accessing your machine directly. I guess it would depend on how serious you felt the risk was. Like any application, "firewall" software can be simple or highly complex, with the more complex costing more and providing more "features" presumably.

If you have a dynamic IP number that only gets assigned to your machine when you start a session, then the risk is much lower that you would be seen as a possible target by a hacker.

A hacker who gains access to your machine can then read from it any data he wants; and he can cause it to slavishly participate in a wide-area distirbuted "denial of service" attack as described above by sending it orders to flood a chosen target with "packets" -- strings of high/low voltage representing logical bits which are bundled together and usually make up larger messages when re-assembled.

This is another reason I like recommending Macs to people. They are much harder to hack, because of their architecture, although with the advent of OS X they are just about as vulnerable as any UNIX server.

That's about all I know in it, LH. If you need a detailed analysis, you need a hands-on geek.

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