Second, many corporations have policies regarding the acceptable use of the corporate network, and fire walls can be used to enforce those rules. For example, I doubt your boss wants you surfing the Playboy Web site while you're supposed to be working on his presentation. A fire wall can keep you away from certain sites all the time, or only allow you to surf them on your lunch hour. Understanding Packet Protocol Explaining how a fire wall works is tricky without first giving some background on how data is transmitted on a network. When you use a browser and ask for information, say you click to this page, your request goes to a server, which retrieves the data you want.
Fire walls are smart listening devices that understand the protocol of how packets are transmitted.
It's up to your information systems department to install and configure a fire wall. If you think you need one to protect your department's data from snoops, you should contact them and ask. My advice to anyone doing business on the Internet is to get some kind of packet filtering device to protect your data. It's only a matter to time until someone finds a way into your network and steals information. Of course you'll get a fire wall then, but it will be too late.