A firewall can loosely be defined as a structure that is built to protect you from getting burned.

Your home is accessible via a network of interstates, highways, county and city roads and finally, the street that leads to your driveway. (This is the internet.)

When traveling to and from your home, there are other travelers sharing the same roadways in order to reach their own destinations. There is nothing to stop these travelers from traveling the same roads you use or visiting your house. (Your PC)

As a homeowner, you wish to filter those you wish to visit from those you do not. There is a variety of means by which you can do this. You can post no solicitors sign to discourage door to door salesmen, (Disabling Java, Java Scripting and ActiveX controls and refusing cookies.) but these tactics will have little influence on the dedicated burglar. (Hackers)

I think all of you will agree that the security of your property and family is a major concern. You take appropriate steps by locking your doors and windows, you safeguard your valuables and try to make your home as unappealing to a burglar as possible. These steps don't necessarily mean that you won't be burglarized.

Wouldn't it be nice to have your own personal Security Guard to monitor yours doors and windows? How about one that will go so far as to screen your phone calls for you, allowing only calls that you want?

Basically, a firewall acts like a gatekeeper you station at the doorway to your internet connection. All traffic is routed through the firewall before it ever reaches your PC and is inspected using a strict level of protocols to determine whether or not the communication is safe or not, and then whether or not it is a communication that you wish to receive.

By now, you are aware that there are ports on your PC. Printer ports allow your PC to communicate and transmit data to your printer, which in turn receives and interprets the transmission and then prints a page based on this communicated data. If you have an active sound system, your speaker ports receive data transmissions from your sound card which it interprets and is manifested in the form of sounds you hear.

You are then aware of the phone line port that is connected to your modem. It would seem reasonable to consider that port as singular. That is not the case. Your internet connection is appraised of more than 65,000 ports, or doorways that data packets can access your PC.

Different types of transmissions use different ports, the best known of these ports are numbered from 0 to 1024, these ports adhere for the most part to strict protocols which are strictly adhered to. A connection at port 80, for example, is almost always used to connect to a web site (http), though ports 8080 and 1024 are used for this purpose as well.

Ports numbered greater than 1024 are not bound specifically bound to any certain protocol, any number of servers can use these ports.

When a server or program attempts to connect to your internet connection, it is preceded by a data packet that basically describes the transmission protocol.

A firewall is used to intercept and interpret these data packets and to accept or reject the transmission based on both user defined and pre configured rules that the software manufacturer sets in place.

A firewall will also monitor the traffic that is transmitted from your PC in the same way, allowing you to determine which programs you have installed to access the internet. This can be very important if you are ever infected with a Trojan virus. In fact, it can save your personal and financial data from being transmitted across the internet.

Hardware firewalls range in price from about $125.00 to $200.00 dollars for the average internet user or small network to more than $100,000.00 for the great monsters that the huge corporations often use.

Software firewalls range from freeware to about $50.00. These programs are ideal for the average internet user.

It's very simple. Depending on the firewall and how you have it set up, generally an alert of some unauthorized connection attempt will result in an 'alert' box popping up onto your monitor. It will either notify you that the connection attempt has been blocked, or ask if you if you would like to allow this connection to take place.

So if I set up my firewall and have cookies Java, Java scripting and ActiveX disabled, then I am worry free. Right?

No, if a hacker really want's to get into your system, he/she will find a way. There is more that you can do to ensure your personal and financial data from being transmitted randomly across the internet.