You’re having a private party and it’s strictly by invitation. But you know that people will not stop from coming to try and crash the affair.

So, to make sure that only those invited can enter the venue, you set up a reception area where arriving guests are carefully screened. Those who can show a proper invitation are let in. Those who can’t are politely sent away.

The reception area is an example of a firewall. It’s a system or program designed to filter incoming traffic so that unauthorized Internet users are blocked from entering private computer networks and causing damage.

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