Historically, firewalls were a means to keep fires from spreading. They were barriers, generally made of stone or some other non-flammable material, that were placed between houses or apartments or even sections of towns to prevent a fire in one place from threatening another. Networking folks got a hold of the term and made it their own. Firewalls now commonly refer to the means by which we prevent certain types of data flowing from one computer to another.
Not all data is bad, and most of the data we see is Internet stuff: web pages, email, instant messages and the like. These are the kinds of data people want to access. But other kinds of data are not so good, some of it being personal in nature or outright malicious, and we want to prevent this data from either leaving our computers or invading them.
Thus the need for firewalls.
Firewalls comes in two kinds, hardware and software, and both of them intend on keeping our computers, our data and our networks safe. With a firewall we can say what kinds of software we want talking on a network, we can decide what kinds of data our computer will accept, and we can set a certain level of trust between computers on networks we own. A firewall is a tool we use to keep the bad guys out.
Will you need to know how a firewall works in order to use it? That depends on what you want to do, but most users can download a software firewall that comes preconfigured so the user needn't do much at all but install it. These kinds of firewalls are easy to install, and they take but a download and a few clicks of the mouse to set them up right away.
The University of Nebraska at Omaha does not offer firewall software itself. However, several vendors, all of them outside the University, do offer personal firewalls for free or at a significantly reduced cost. We provide links to them below. And if you are feeling curious, we also provide a couple links to sites that explain extensively what firewalls are.