Firewalls have helped protect computers in large companies for years. Now, they're a critical component of home networks, as well. See more computer networking pictures.
firewall diagramIf you have been using the Internet for any length of time, and especially if you work at a larger company and browse the Web while you are at work, you have probably heard the term firewall used. For example, you often hear people in companies say things like, "I can't use that site because they won't let it through the firewall."