It is similar to a physical firewall in a building - a floor to ceiling barrier designed to prevent fire spreading over into another room. In computer terms it is usually a piece of software or hardware (or both in combination), its function being to put a protective "wall" around sensitive processes or data on a system. The protection is two way; stops you getting in (if you dont have necessary authority, and prevents unwanted "leakage" of data on the way out.
it is only recently that i understood this too
your computer can usually do more than one thing at a time. if you are using it and someone tries to access it sometimes your computer starts acting funny when you're using it. i think it has to be connected to a phone line or network though. a friend of mine had a g4 cube (which is normally very fast)go really slow and make funny sounds when he was connected online. as soon as he unplugged the cable it stopped. he'd plug it in and it started again. we finally figured that someone was getting in and using his computer to run a program or process large amounts of information.
firewalls also stop you from going to places and doing things that makes your computer accessible to others. good luck with it all.
If you have a cable connection, a firewall is a fairly necessary utility, because you're ports are always accessable...however, with a dialup connection, it's relatively unlikely that you really need a firewall utility on your computer. With cable your IP is always the same, so you're highly vulnerable to attacks, but with a dialup, you get a new IP everytime you connect...the chances of someone hacking that particular IP are minimal.
Thank you all! Finally some informatin that is in english and not computer jargon! I really do not feel I need one myself but my daughters company has one and it often keeps her from recieving e=mails that are from "unauthorized" servers. So it had me curious. Since I have a dial up connection it sounds like I really so not need it at home.
To be a little more specific...your computer has over 2000 ports. Certain ones are "program specific" such as a mail port, browser port, etc. By having a firewall utility, you specify which applications are allowed to have access into your computer. For instance, if you have ICQ, and trust that application, you allow ICQ access to the port it uses to enter your computer.
As I mentioned, with a dialup connection, you get a new IP everytime you connect. An IP is the address of your computer. It might look like "18.104.22.168"...something like that. I have cable, which gives me a "static IP"...it's always the same. I could be hacked fairly easily, without a firewall. I STILL can be, but someone would have to come in through those applications I allowed to have access. It wouldn't be easy. Most people do not firewall dialup connections.
I have firewalls installed via http://www.zonelabs.com. They have three choices: the first one which I have is free and seems to work very well. I've never had anyone accessing my computer (that I know of) and have yet to get a "virus". This was recommended by a computer group I go to once a month.