In real world a "fire wall" is a fireproof wall that is built to stop spread of fire from one part of a building to others. In Internet world a firewall has a similar purpose in that it stops spread of harmful viruses and attacks from entering your home or office network. Because of ever-increasing threats that are appearing on Internet you no longer have to be in business to need protection of a fire wall. In fact, every computer that is connected to internet should have one installed. You'll be a lot happier once you know that you have protected your personal files, information, and financial data, such as credit cards and bank account numbers, from being shared with every crook on internet.
Here are some questions that you should consider before you choose a fire wall for your PC:
1. What features do I need?
2. Do I want to be protected from viruses, Trojan horses and worms?
3. Am I at risk because I use programs that access Internet automatically?
4. How much am I willing to spend on a firewall solution?
Here are common features that are available in almost any software-based fire wall program:
Inbound filtering - protects unknown users or programs from accessing your PC
Outbound filtering - Protects your PC from sending information to Internet without your permission
Application integrity verification - Verifies that any program you are running aren't sneaking around behind your back and doing things that they shouldn't be doing.