What is a Firewall?

Learn about the key software that keeps your computer safe from viruses.

Did you know that computers have what’s called a “firewall”? Don’t worry; it’s not going to burn you or your computer! In fact, firewalls don’t have anything to do with fire.

Despite this, a firewall is a very important part of your computer’s security. That’s because it looks at all the data coming in and going out, and finds anything that looks off or bad. If something doesn’t look right, it blocks that connection and protects your computer.

When you use the computer to connect to stuff outside of it (like going on the internet), your computer sends the data through what’s called a “port.” It’s worth imagining these as boat ports, where ships can leave and enter through them.

If a port doesn’t have any security, everything runs smoothly as long as every boat plays by the rules. If boats use the ports to deliver cargo and people, and nothing shady happens, then everything is fine.

Unfortunately, things aren’t always fine! What if ships start trying to smuggle in illegal goods in their cargo? Maybe even pirates can dock and cause trouble! The best way to stop this is to check each boat coming in to ensure its sailors and its cargo is all legal.

This is what a firewall does for your computer’s ports. It checks if all the connections being made are behaving and doing well, and blocks anything that’s unwanted.

For the firewall to do its job, it needs “rules” to work with. Computers can’t work well with concepts, such as “draw a cat” or “what does happiness feel like”. They do, however, work very well with logic-based rules. As such, a firewall has a lot of rules that it applies to data going in or out to see if it’s allowed or not.

When you install a new program that uses the internet, the firewall may not know what to do with it. That’s why you’ll sometimes see a pop-up from your firewall asking you if it’s okay to let the program to connect to the internet. You usually add an exception to the firewall’s list of rules to allow the program to connect to the internet.

Now you can see why it’s important to have a firewall turned on when you’re surfing the internet. As you browse, connections are being made on your computer’s ports, and data is traveling in and out of them. A firewall helps keep nasty people from getting access to your computer through these ports, so be sure to turn it on while you surf!

So, a firewall is sort of like a wall and has nothing to do with fire. But if that’s true, why does it have that name in the first place? You may be surprised to know that the term ‘firewall’ actually comes from building construction.

Builders sometimes separate buildings or parts of a building with a big wall made of materials that can’t catch fire, such as concrete. That way, if a fire breaks out, it cant spread past the wall. This is similar to the computer firewall, which stops viruses and hackers from getting past the wall into the computer.

While it has a silly name, firewalls are based on a real-life method to save buildings from fires. While builders use them to protect homes, you should use your own to protect your computer from hackers and viruses!

Learn More

Firewall definition


What is my IP address?


Firewall FAQs


Three types of firewalls


How Firewalls work


Evolution of firewalls


Firewall networking


Why are firewalls important


Kid Safety in Digital Age


Origin of term “Firewall”


Firewall construction



  • Simon Batt

    Simon Batt is a UK-based tech enthusiast and all-around geek. His favourite things are cups of tea, cats, and new gadgets, even though they never mix well.

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