In the old days if someone wanted to sneak into your computer, they would have to physically break into your home or office and use your computer without your knowledge. Stopping these types of intruders was as easy as locking your Macintosh in a sealed room.
However, the latest danger is that someone can access your computer remotely through the Internet. You could even be using your computer and not know that someone else is quietly sneaking into your Macintosh and stealing data right in front of you.
To stop intruders from accessing your computer through the Internet, you need to use a program called a firewall. The main idea behind a firewall is that it blocks suspicious or invalid data while letting in the data that you need or want.
Think of a firewall as an intelligent doorman who tries his best to open the door to your Macintosh only to authorized data and slam it shut against malicious data.
Project goal: Learn how to protect your Macintosh with a firewall.