The Computer Revolution/Firewall
What a firewall is 
A firewall is a type of security for computers both personal and business. A firewall is produced as software or hardware and can be installed onto a computer. The main purpose of a firewall is to examine all the information entering a computer. If the information entering a computer fails to meet a certain criteria the information will not pass through into the computer. The entire purpose behind a firewall is, in the easiest words "to keep the bad out and the good in." It monitors the traffic of your computer. What is going out and what is coming in. It makes sure that you do not have to many vulnerabilities and that the information that is coming in is nothing malicious and that the information that is going out is not your essential information that needs to be kept on your computer. Although firewall is made for this purpose, firewall cannot always keep out all viruses and is not fool proof so it is still important to practice safe browsing. Firewalls are often built into your computer operating system but many times, it is just the basic. It is always good to browse around for a good firewall program, as many of them are set up to do different things and have different levels of security. Upon choosing the firewall that you feel is good for you, it is always important to uninstall the one that you have, as two firewalls running at once can cause major damage to your computer. []
How a firewall works 
There are many techniques used by a firewall to monitor and sort the information accessing your computer. Some of these techniques are packet filters, application gateways, circuit gateways and proxy servers. All of these techniques work off a different characteristic to sort through potential dangerous files to safe files. But the most common aspect found between these techniques is the principle of checking the data through the information which is available. This includes a user defined criteria, a process of monitoring and checking FTP as well as TCP. And in some cases once a firewall has established a secure line to receive information from a server, information can freely flow without being checked.
How you obtain a firewall 
You can purchase software which will have a firewall built into it. Other firewalls can be purchased independently and installed along with other anti-virus software. Some of the main company’s which produce firewall software are McAfee, Norton, Microsoft and Apple. After purchasing firewall software you then follow the installation instructions provided and configure the firewall to your criteria for safe files and potential dangerous files.