For one to understand the intentions of personal firewall software one needs to think of a locked door or a safe.
The intention of personal firewall software is to not let anything in or out of your computer it deems as a threat unless you say so, or at the very least least not without your knowledge.
Firewall software has been around since 1988 and basically what it does is secure your internet connection by filtering packets going in and out of your computer. Packets being information that is transferred between your computer and the internet. It tirelessly searches for threats that may harm your computer and or your internet connection. Having a personal firewall on your computer these days is just safe practice. Unlike in 1988 when the first computer worm was written which is why personal firewalls were created, such threats were not prevalent. The internet was in its infancy and firewalls for the home computer were not really necessary. Then came Windows 95 and the internet .com boom, threats and worms were starting to be written more vigorously. Since then it has been a race between the writers of these threats and security software companies to combat those threats.
These days new threats are being written every day and if you were to surf the internet without a firewall it would be safe to say that your internet connection and or your computer would be compromised within a week or less. This is why unlike antivirus software if your firewall pops up and shows you a threat or intrusion , you need to pay attention to it and not shrug it off.
Just think of your computer as a bank with a safe in it, there are lots of people that would love to get into that safe and take that money, right? Well that’s what a firewall does, it acts as a safe that secures all that precious information that you cannot afford to get into the wrong hands. That is the intention of personal firewall software in its simplest terms.